What began the development of the two distinct european civilizations of the western roman empire and the eastern byzantine empire?

If the choices are:

A.  Leaders of the Catholic Church had a major disagreement in the seventh century.

B.  In the sixth century, trade flourished in the eastern regions but not in the west.

C.  Around 400 C.E., Germanic tribes took over much of the empire's western territories.

D.  In 395, the sons of Theodosius I each became emperor of part of the empire.

The correct answer is:  D

what are the options?

the answer is a, salt plain