Y2 Phys Exam Review not final

59 years old female presents to ER with quadriparesis, dysarthria. On examination patients eye movements are affected and patient report Diplopia? Lesion of which artery is the possible cause of patients symptoms

a) anterior cerebral artery stroke

b) basilar artery stroke

c) middle cerebral artery stroke

d) posterior cerebral artery lesion

b

58 years old alcoholic man, reports to doctor for unsteady balance and repeated falls. On examination patients has pars pointing (dysmetria), abnormal rapid alternating movements and abnormal heel to shin test. Lesion of which brain structure is responsible for patient's signs and symptoms?

a) lesion of the cerebellar hemispheres (lateral)

b) lesion of the cerebellar vermis

c) basal ganglia

d) brain stem lesions

a

87 year old man presents with step wise progressive memory loss.. His memory is stable for some time then deteriorates. Patient also exhibits difficulty in planning and executive functions. Patient's history is significant for high blood pressure and stroke. On examination patient has slurring of speech and is not fully oriented to time and place but is oriented to persons. What is the most probable diagnosis of patient's memory loss?

a) Alzheimer's dementia

b) dementia secondary to Parkinson disease

c) multi-infarct dementia

d) lewy body dementia

c

20 year old patient was involved in 3 accidents in the last months. He tells doctor that he follows all driving rules such as he signals before changing lanes and checks his mirrors and blind spots but he is unable to see car in his blind spot. Which cranial nerve is possibly involved?

a) olfactory nerve

b) vagus nerve

c) optic nerve (optic chiasma)

d) trigeminal nerve

c

45 years old man had a motor vehicle accident. After the accident patient suffers with tinnitus is unsteady and prone to falls. Which cranial nerve is possibly damaged as result of the motor vehicle accident?

a) optic nerve

b) facial nerve

c) trochlear nerve

d) vestibulocochlear nerve

d

26 years old woman consults neurologists with relapsing and remitting muscle weakness, numbness and tingling sensation in the left leg trunk. She has Dysarthria, walking difficulty and vertigo. On examination patients has brisk deep tendon reflexes, spastic paralysis and gait ataxia. The MRI showed demyelination in the cerebellum and brain stem. Abnormality of which cell is responsible for the underlying pathology?

a) oligodendrocytes

b) astrocytes

c) ependymal

d) neurons

a

27 year old man suffers concussion as result of the motor vehicle accident. He reported leakage of CSF from the nostrils. After the accident patients reports altered sense of smell and he is unable to smell fragrances and odors. Which cranial nerve is possibly damaged as result of the motor vehicle accident?

a) vagus nerve

b) olfactory nerve

c) optic nerve

d) trigeminal nerve

b

Which brain structure is involved with the sleep awake cycle, regulation of the pituitary gland and autonomic system?

a) subthalamus

b) pineal gland

c) thalamus

d) hypothalamus

d

Mr. Parkinson is a 80 years old man, who has noticed tremors in his both hands but more in right hand. He has difficulty in getting out of the chair. His voice has softened over the last few months. People have told him that he is less expressive through his facial expressions. His hand writing has changed and writes with smaller letters. He has fallen few times over the last 2 months, particularly when going through doors or narrow spaces. What is most probable diagnosis?

a) stroke/cerebrovascular accident

b) basal ganglia (Parkinson disease)

c) hyper secretion of thyroid functions

d) cerebellar disease

b

What brain structures play role in the implicit memory (unconscious memory)?

a) basal ganglia, cerebellum, motor cortex, Amygdala

b) cerebellum. Pons, pineal gland, hypothalamus and pituitary gland

c) brain stem, corpus collusm, ventricles

d) pons, medulla, brain stem, basal ganglia

a

36 years old woman consults neurologist with relapsing and remitting muscle weakness, numbness and tingling sensation in the left leg trunk. She has dysarthria, walking difficulty and vertigo. On examination patients has brisk deep tendon reflexes, spastic paralysis and gait ataxia. The MRI showed demyelinationin the cerebellum and brain stem. What is the most probable diagnosis or possible causes of patient's symptoms?

a) peripheral neuropathy

b) lumbar disc herniation

c) multiple sclerosis

d) conversion disorder (psychological condition)

c

Mr. Parkinson is a 80 years old man who has noticed tremors in his both hands but more in right hand. He has difficulty in getting out of the chair. His voice has softened over the last few months. People have told him that he is less expressive through his facial expressions. His handwriting has changed and writes with smaller letters. He has fallen few times over the last 2 months, particularly when going through doors or narrow spaces. What other brain structure will you try to rule out during the history and examination

a) pons

b) cerebellar lesion

c) medulla oblongata

d) basal ganglia lesion

b

28 year old woman consults neurologist for drooping of the right angle of mouth. She also reports that when drinking, water drools from her right side of the mouth. On examination she is unable to puff her cheeks, and smile but she is able to frown. What is the lesion?

a) upper motor neuron lesion of the facial nerve

b) palsy of the trigeminal nerve

c) glossopharyngeal nerve paralysis

d) lower motor neuron lesion of the facial nerve

a

18 years old man has presented with flining semi-purposeful dancing movements. He has psychiatric manifestations such as hallucinations and depression. He also report progressive memory loss. His father and grandfather the similar symptoms. What is the most probable diagnosis?

a) cerebellar disorder

b) mid brain lesion

c) Parkinson's disease Caudate nucleus (Huntington's chorea)

d) Caudate nucleus (Huntington's chorea)

d

59 years old female presents to ER with quadriparesis (all 4 limb paralysis), dysarthria (difficulty in articulation). On examination patients eye movements are affected and patient report Diplopia (double vision)? Lesion of which artery is the possible cause of patients symptoms

a) posterior cerebral artery lesion

b) anterior cerebral artery stroke

c) basilar artery stroke

d) middle cerebral artery stroke

c

What brain strucutes play role in the explicit memory?

a) medulla, pons, brain stem

b) hippocampus and parahippocampal

c) sub thalamus, epithalamus, pituitary gland

d) pineal gland, hypothalamus, thalamus

b

58 year old alcoholic man reports to doctor for unsteady balance and repeated falls. On examination patients has truncal ataxia (sway of the body) when his eye were closed? Lesion of which brain structure is responsible for patient's signs and symptoms?

a) Lesion of the cerebellar vermis

b) lesion of the cerebellar hemispheres (lateral)

c) basal ganglia

d) brain stem lesions

a

78 year old man presents with right leg paresis and loss of sensation in the lower extremities. The MRI shows infarct. Lesions in which vessel territory can give symptoms that patient have?

a) middle cerebral artery

b) basilar artery

c) anterior cerebellar artery

d) vertebral artery territory

c

65 years old woman present to spine surgeons with bilateral leg weakness, paresthesias and leg pain. Patient pain increases with prolong sitting or standing but reduces in intensity when she changes her position. Pain also increases with extension at the low back pain. What is the most probable cause of this womans sympotms?

a) spinal stenosis causing neurogenic claudication

b) cauda equina syndrome

c) lumbar disc herniation

d) low back sprain

a

Multiple Sclerosis is caused by

a) absence of schwann cells

b) inability to release neurotransmitters

c) absence of axon terminals

d) deterioration of patches of myelin

d

20 year old man was involved in a MVA. After the injury, he presents with bilateral hand weakness and muscle wasting. He also has reduced appreciation of the pain and temperature in upper extremities but has preserved touch and joint position sense in the neck, shoulder and arms bilaterally. What is the most possible cause of patients symptoms?

a) central cord syndrome

b) posterior cord syndrome

c) anterior cord syndrome

d) Brown Sequard syndrome

a

78 year old man seeks medical attention for Paresthesia for the last 1 year. Patients report burning sensation in the hands and feet bilaterally and reports weakness in his hands and legs. His medical history is significant for diabetes mellitus. He had MVA 10 years ago. He works as a human resource manager. what is most common cause of his symptoms?

a) this man is functional

b) diabetes mellitus

c) his work and prolong sitting is the cause of his symptoms

d) MVA causing bilateral leg and hand paresthesia

b

20 year old man presents to with wrist drop. When patient is brought to the ER, ER physician smells alcohol from his breath. Paramedics note shows that he was found unconsciuos on the bench with his hand hanging down the backrest. What is the most probable cause of his wrist drop?

a) radial nerve injury

b) ulnar nerve injury

c) alcoholic neuropathy

d) median nerve injury

a

25 year old man had a motor wehicle accident. After the accident, he complains of neck pain that radiates down to his hand. He is unable to extend his arm and on examination his tricep reflex is absent. Which nerve root can be potentially be affected

a) T1 radiculopathy

b) C6 radiculopathy

c) C5 radiculopathy

d) C7 radiculopathy

d

67 year old man with known prostate cancer is brought to the ER for sudden onset bilateral leg pain weakness. This patient is unable to weight bear and ankle reflexes are absent bilaterally. n examination patient has reduced anal tone and saddle anesthesia. Patient is also unable to urinate. What is the most probable cause of patient's symptoms?

a) cauda equina syndrome

b) bilateral neuropathy

c) spinal stenosis causing neurogenic claudication

d) low back sprain

a

29 year old pregnant woman consults her family physician for Parestheisa in her hands. Her symptoms such as Paresthesia increase during the night time and wake her from her sleep. She does not recall any injury to her hands. Her prenatal examinations are up to date. On examination, when you tap her wrist patient reports tingling sensation going to her thumbs, index and middle finger. When you ask patient to flex her hands at the wrist, her hands get numb. What is the most cause of her symptoms?

a) median nerve entrapment

b) radial nerve entrapment

c) no issues with her hand, patient is functional

d) ulnar nerve entrapment

a

25 year old man is brought to ER with progressive bilateral leg weakness. The weankness is ascending proximally. On examination doctor notices bilateral absent loss of ankle reflex, flaccid weakness of the legs bilaterally. Patient also has bilateral symmetric paresthesias, loss of proprioception and vibration sense. Patient suffered gastroenteritis few weeks before his symptoms started. He does not recall any injury or trauma to his legs. What is the most probable diagnosis?

a) spinal cord infarction

b) Guillian-Barre Syndrome

c) Multiple sclerosis

d) Cauda equina syndrome

b

45 years old man present to ER with sudden onset low back pain. Pain started when he was lifting a metal sheet in the factory. He felt a popping sound in his low back. Pain radiates to his leg and big toe. He is unable to walk on his toes. On examination patient is unable to walk on tiptoes. What is the most probable cause of the patient's symptoms?

a) lumbar vertebra fracture

b) low back sprain

c) low back sprain

d) S1 radiculopathy

d

18 year old girl was camping with her family. During the night she woke up with severe burning left leg pain. She consulted her doctor for pain. On examination doctor noticed her leg is relatively swollen than the left leg, right leg is red and when doctor touches her leg and foot her pain increases. She does not recall any insect bite or any major injury to her legs except for a minor fall and few abrasions to her legs. What is the most probable cause of her symptoms?

a) complex regional pain syndrome

b) insect bite

c) she is functional, nothing is wrong with her leg

d) neuropathy

a

20 year old women complaints of easy fatigability and tiredness. She feels better in the morning but by the end of the day, she is more weak and tired and has difficulty in completing her chores. Rest makes her feel better. By the end of the day her right eyelid droops. What is the most probable diagnosis?

a) Myasthenia gravis

b) Gullian Bare Syndrome

c) Neuropathy

d) this is a normal phenomena

a

20 year old women, complains of easy fatigability and tiredness. She feels better in the morning but by the end of the day, she is more weak and tired and has difficulty in completing her chores. REst makes her feel better. By the end of the day her right eye lid droops. One of the important differential diagnosis is myasthenia gravis, which is a neuro-muscular junction disorder. Which neurotransmitter is mainly required to facilitate nerve transmission at the NMJ?

a) acetylcholine

b) nitrous oxide

c) epinephrine

d) GABA

a

The first heart sound is due to closure of which valve?

a) atrial valve at the vena cava

b) pulmonary valve

c) mitral and tricuspid valve

d) aortic valve

c

Which brain structure is mainly responsible to control heart activity such as heart rate, contraction, conductivity?

a) carotid sinus chemo and baroreceptor

b) medulla oblongata at the brain stem

c) cerebral cortex

d) baroreceptors

b

69 year old unconscious man is brought to ER via ambulance. In ER, his blood pressure is 60/40, pulse is palpable. Following is the EKG of the patients. What is the most probable diagnosis

a) wolfmann's Parkinson white syndrome

b) atrial flutter

c) ventricular fibrillation

d) atrial flutter

c

65 year old patient presents to ER with symptoms consistent with stroke. On examination patients has irregularly irregular pulse and absent P waves on the EKG/ECG. Following is the EKG What is the diagnosis based on the EKG finding?

a) atrial fibrillation

b) myocardial infarction

c) sinus tachyarrhythmia

d) ventricular fibrillation

a

80 years old man suffered with myocardial infarction. On examination patient has hypotension (low blood pressure) and slow heart rate (Bradycardia). Infarction of which structure is most likely responsible for patient's low blood pressure?

a) AV node

b) bundle of his

c) purkinje fibers

d) sino-atrial node (SA node)

d

60 year old man presents to cardiologist for progressive short of breath (SOB). Patient also reported pink frothy sputum, chest pain and feels funny sensation in his chest. His past history in significant for myocardial infarction 6 months ago. On chest examination, physician finds murmur consistent with mitral regurgitation. What is the most common cause of patients SOB?

a) left heart failure secondary to myocardial infarction

b) right heart failure

c) Constrictive pericarditis

d) heart failure

a

Which of the following is true about the ventricular isocolumetric contraction?

a) pushes AV valves closed but does not create enough pressure to open semilunar valves

b) fall in ventricle pressure and backward blood flow to snap the semi-lunar valves

c) both sets of the ventricle are relaxed and ventricles fill passively

d) atrial contraction forces small amount of blood into ventricles

a

80 year old man suffered with myocardial infarction. On examination patient has hypotension (low blood pressure) and slow heart rate (Bradycardia). Infarction of which artery is mainly responsible for patients hypotension?

a) left circumflex artery

b) right coronary artery

c) left anterior descending artery

d) intercostal artery infarction

b

80 year old man suffered with myocardial infarction. What is most likely EKG finding?

a) no specific pattern

b) ST segment elevation

c) absent p-waves

d) peaked T waves

b

80 year old man report chest pain exertion. Pain resolves with rest but recurs with the exertion. Another relieving factor is nitroglycerine. Cardiac enzymes are normal. What is the most probable diagnosis?

a) pericarditis

b) unstable angina

c) stable angina

d) myocardial infarction

c

53 year old man presents with left retrosternal chest pain and shortness of breath. Chest pain gets better on leaning forward. On examination patient does not have murmur but pericardial knock is audible?

a) constrictive pericarditis

b) pleuritis (inflammation of the pleura)

c) pneumonia

d) pericardial tamponade

a

Second heart sound is due to the closure of which valves?

a) aortic and pulmonary valve

b) mitral valve

c) tricuspid valve

d) atrial at the vena cava

a

80 year old man suffered with myocardial infarction. Which cardiac enzyme is more specific to myocardial infarction?

a) troponins

b) creatinine kinase

c) AST/ALT (SGPT?SGOT)

d) there is no specific cardiac enzyme

a

58 year old man presents to cardiologist for swelling of legs bilaterally. His past history is significant for myocardial infarction 6 months ago. The cardiovascular examination reveals murmur consistent with mitral regurgitation, pulsus alternans and peripheral cyanosis. Physician diagnosis patient with left ventricular failure. What is the most probable cause of patient's SOB/ left ventricular failure?

a) high salt intake

b) poor medication compliance

c) myocardial infarction

d) high blood pressure

c

53 year old man presents with left retrosternal chest pain and shortness of breath. On auscultation, heart sounds are muffled. Further examination shows elevated and positive pulsus paradoxus. What is the probable diagnosis?

a) Pleuritis

b) pneumonia

c) constrictive pericarditis

d) pericardial tamponade

d

60 year old man presents to cardiologist for swelling of legs bilaterally. His past history is significant for myocardial infarction 6 months ago. On chest examination, physician finds murmur consistent with tricuspid regurgitation. Patients jugular venous pulsation is elevated, has pulsatile liver. Patient does not have pulsus paradoxus. What is the most common cause of patient's peripheral edema?

a) constrictive pericarditis

b) left heart failure

c) pericardial effusion

d) right heart failure secondary to myocardial infarction

d

19 year old patient presents to ER for increase heart rate, sweating and increased anxiety like symptoms. On examination patient has irregularly irregular radial pulse. Physician diagnosed patient with atrial fibrillation. What will possible finding on EKG/ECG?

a) absent P waves

b) peaked T waves

c) ST segment elevation

d) prolong PR interval

a

61 year old man suffered myocardial infarction 2 days ago. On 3rd day patient report chest pain, which relieves with leaning forward? Patient also report shortness of breath. On auscultation patient has pericardial rub. What is the most probable diagnosis?

a) Dressler syndrome

b) costochondritis

c) pericarditis

d) diffuse esophageal spasm

c

53 year old man suffered with the lung cancer for which patient required chest radiation to eradicate tumors. Patients have shortness of breath and retrosternal chest pain. On examination, patient has pericardial knock is audible. Further examination showed elevated jugular venous pulsation (JVP), pulsatile liver and liver enlargement?

a) pneumonia

b) pericardial tamonade

c) pleuritis (inflammation of the pleura)

d) Constrictive pericarditis

d

20 year old man was playing basketball when he collapsed suddenly. Ambulance was called to the scene. On the intial assessment, patient was not breathing and pulse was not palpable. Patient was taken to hospital where emergency physician declared him dead. What is the most probable cause of patient sudden death?

a) restrictive cardiomyopathy

b) no abnormality in the heart

c) hypertrophic cardiomyopathy (HOCM)

d) dilated cardiomyopathy

c

A 3 year old previously healthy child is brought to ER with a painless lump on his foot of several weeks. He does not have fevers, the lump is not red and not painful. A biopsy of the lump demonstrates fibrosis. Other expected findings on this biopsy could include:

a) neutrophils and small foreign body

b) neutrophilic and bacteria

c) macrophages and foreign body

d)" monocytes, lymphocytes and bactera

c

A 40 year old woman has had a chronic cough with fever and weight loss for the past month. A chest radiograph reveals multiple nodules with cavitations suggestive of Tuberculosis. Which cells is the most important in the development of this lung lesion?

a) platelet

b) mast cell

c) macrophage

d) neutrophil

c

A 40 year old woman has had a fever and cough over the past 2 days. The patient was treated for acute chest infection requiring antibiotics. After the antibiotic course, the patient still has a fever but a cough has subsided. The X ray showed cavitary lesion with an air-fluid level. Which of the following is the best description for this outcome of her pneumonia?

a) bronchogenic carcinoma

b) progression to chronic inflammation

c) abscess formation

d) regeneration

c

A 58 year old woman has consulted family physician for a acute cough and fever of 3 days. Physical examination showed pharyngeal purulent exudates. Which of the following types of inflammation did these patients most likely have?

a) chronic inflammation

b) abcess formation

c) granulomatous inflammation

d) acute inflammation

d

Which of the following processes is not typically involved in the acute inflammatory process?

a) apoptosis

b) diapedesis

c) margination

d) rolling

a

A 15 year old girl known to have cystic fibrosis is hospitalized for acute exacerbation pneumonia. The microscopic examination of the trachea-bronchial wash, showed neutrophils, macrophages and large numbers of bacteria. All of the following are supported EXCEPT?

a) an allergic reaction

b) acute inflammation

c) an infection

d) chronic inflammation

a

Which of the following is true about the anphylaxis process such as insect bite or allergic reaction in the acute inflammation?

a) formation of granulomas

b) stimulation of vaso active compounds and vasodilation

c) macrophages and lymphocytes migration

d) the release of acute-phase cytokines and neutrophils

b

The process through which neutrophils migrate towards the inflammatory focus after extravasations is known as:

a) margination and rolling

b) diapedesis

c) adhesion

d) chemotaxis

d

23 year old man is suffering with acute bacterial infection. Which cell count will be elevated?

a) neutrophils

b) lymphocytes

c) macrophages

d) basophils

d

12 year old boy was playing soccer when fell down. He got few abrasions on his knee. Bleeding stopped 1-2 minuites after the injury. Which cells are mainly involved in stopping the bleeding initially:

a) platelets

b) neutrophils

c) red blood cells

d) macrophages

a

Which of the following types of necrosis is most commonly associated with the ischemic injury?

a) coagulative necrosis

b) caseous necrosis

c) liquefactive necrosis

d) fat necrosis

a

45 year old man has fallen when working. He took over the counter pain killer such as non steroidal anti-inflammatory drug. This medicine will reduce which of he following function of the acute inflammation?

a) Pain

b) scar formation

c) liquefactive necrosis

d) throbosis

a

Which of the following trigger/cause inflammation?

a) physical agents such as injury, trauma

b) all of the listed

c) chemical agents such as acids, alkali

d) biological agents such as virus, bacteria's

b

15 year old girl has allergic rhinitis such as sneezing with watery eyes and runny nose for the past 2 weeks. On physical examination, she has red, swollen nasal mucosal surfaces. She has had similar episodes each spring and summer when the amount of ragweed pollen in the air is high. Her symptoms are most likely to be mediated by the release of which of the following chemical mediators?

a) platelet- activating factor

b) tumor necrosis factor

c) histamine

d) complement C3b

c

15 year old boy was playing outside when he developed a sudden asthma attack. Which cell is mainly involved in the allergic reactions?

a) macrophages

b) eosinophils

c) monocytes

d) neutrophils

b

Which of these is not a clinical feature of inflammation?

a) heat

b) redness

c) necrosis

d) pain

c

27 years man, presents with low grade fever, night sweats and weight loss. He has multiple sexual partners and does not use protection. His recent investigations are positive for HIV infection. Which of the following is not true about this patient or infection?

a) this individual is not at risk of developing AIDS

b) The virus and its antibodies are present in the blood

c) this person is prone for opportunistic infection

d) The HIV virus will mainly target CD8+ lymphocytes the number of circulating lymphocytes will decrease

a

20 years old man is recently diagnosed with HIV infection. He has suffered 3-4 pneumonia infections in the last 3 months. HIV virus is known to affect/damage which immune cells?

a) CD 8+ Lymphocytes

b) neurtrophils

c) B-Lymphocytes

d) CD 4 + Lymphocytes

d

20 years old man is diagnosed with the deficiency of C3 component of the complement system. This man is prone to develop what condition/infection?

a) He is prone to develop recurrent pyogenic sinus and respiratory tract infections

b) he is prone to develop heridetray angioedema

c) he is prone to develop nesseria infections

d) he is prone to complement mediated lysis of RBC

a

Which of the following is not a mode through which immunoglobin/antibody will provide defence?

a) opsonization

b) activation of the CD 8+ cells

c) complement fixation

d) Neutralization

b

Which of the following immunoglobulins can cross the placenta?

a) Ig E

b) Ig D

c) Ig M

d) Ig G

d

Which immunoglobulin plays key role by preventing attachment of the bacteria or virus with the mucous membrane?

a) Ig G

b) Ig A

c) Ig D

d) Ig M

b

27 years old man spleen was surgically removed after a motor vehicle accident. This man will require prophylaxis/vaccination to prevent which of the following infection?

a) no vaccination/ immunization required

b) strephococcus pnenumoniae

c) Clostridum difficile

d) cholera

b

27 years old man had motor vehicle accident. He was brought to ER in shock His vitals when checked in ER are: BP= 70/40 mmHg Pulse rate = 150 min: thread pulse respiratory rate= 30 min Temp= 36 C. Patient required exploratory laparotomy (opening of the abdomen). This patient's spleen was removed due splenic rupture (due to MVA). This patient is prone to develop which infection?

a) pneudomonas aeruginosa

b) clostridium botulism

c) clostridium difficile

d) tetanus

a

23 year old women consults her family physician for pain and stiffness in her hand joints. Her examination and lab work is consistent with rheumatoid arthritis (an autoimmune condition). Which hypersensitivity/immune reaction is responsible for this woman's condition?

a) Type 2 hypersensitivity reaction

b) Type 3 hypersensitivity reaction

c) Type 4 hypersensitivity reaction

d) Type 1 hypersensitivity reaction

a

48 year old man had a kidney transplant. If this man's kidney transplant is rejected, it will be because of which immune or hypersensitivity reaction?

a) Type 1 hypersensitivity reaction

b) Type 2 hypersensitivity reaction

c) Type 4 hypersensitivity reaction

d) Type 3 hypersensitivity reaction

c

15 year old boy was eating in a restaurant, when he developed anaphylactic reaction. The restaurant manager is not sure what this boy ate but certainly reaction started after eating a food. He was injected epinephrine at the scene and was taken to ER for further management . Which hypersensitivity reaction could have contributed to this boy's reaction?

a) Type 2 hypersensitivity reaction

b) Type 3 hypersensitivity reaction

c) Type 1 hypersensitivity reaction

d) Type 4 hypersensitivity reaction

c