30. According to the all-or-nothing principle, _____.
A. if all the neurons in a network are not integrated, the "message" carried by the neurons will be lost
B. the amount of time a neuron must "rest" in between firing episodes is stable
C. once the electrical impulse reaches a certain level of intensity (its threshold), it fires and moves all the way down the axon without losing any intensity
D. as a person ages, his or her neurological system slows down and the intensity of neural impulses decreases significantly