Why Were the Carolingians Unable to Hold Their Empire Together

Multiple Choice

Why were the Carolingians unable to hold their empire together after the death of Charlemagne?

A) The kingdom was divided up by Charlemagne's successors and became vulnerable to attacks by invading Vikings, Magyars, and Muslims.
B) The kingdom was attacked by groups of invading Huns, Ostrogoths, and Vandals, who destroyed the administrative institutions that Charlemagne had built up.
C) Charlemagne had refused to ally himself with the Roman papacy, thereby depriving his kingdom of the unifying force of Christianity.
D) Charlemagne's three sons fought bitterly over the spoils of the kingdom, and each allied himself with a different group of foreign invaders in an effort to defeat his brothers.