Which of the following statements about differences in the territorial integrity of the Roman empire ca. 400 C.E. is correct? \n A \n Virtually all the provinces of the Roman empire had been occupied by invading nomadic peoples from northern and eastern Europe, including the Ostrogoths, Visigoths, and Franks. \n B \n Angles, Saxons, Ostrogoths, and Lombards coordinated invasions of Asian and African provinces of the western and eastern Roman empires. \n C \n The Huns, Visigoths, and Vandals had all invaded different parts of the eastern and western Roman empires, but Britain, Egypt, Anatolia, and Syria had yet to be raided by northern nomads. \n D \n The Roman empire was a unified, centralized state whose defenses were adequate to ward off Arab nomads and Sasanid Persians who were attacking Palestine, Egypt, and Syria.