Which statement is the best caption for this map?
A. In A.D. 284, the emperor Diocletian divided the empire in two, naming a co-emperor to rule in the west.
B. In A.D. 284, a new emperor conquered half of the Roman empire, leaving only half under the rule of Diocletian.
C. In A.D. 284, the emperor Diocletian united the Roman empire after years of division.