Answer:
B. The assassination of Julius Caesar.
Explanation:
The Cristianity was adopted as the official religion of the Roman Empire in 380 A.D.
The assasination of Julius Caesar occured in the Roman Senate in the last years of the Roman Republic, to be precise, in 44 B.D. August became the first emperor of the Roman Empire in 27 B.D.
The defeat of Carthage in the Punic Wars occured in 146 B.D.
The division of the Roman empire into western and western empires was done in 395 A.D.
