When diocletian split the roman empire into two parts:
o maximian took the western half
o it had a long run of powerful leaders that maintained control
the weak emperor constantine died
the western empire would overcome the eastern empire

When Diocletian split the Roman Empire in 284 A.D. into two parts he remained in control of the Eastern half while giving the Western half to his colleague Maximian. This happened because when Diocletian took power he was in control of an Empire in decline. The split stabilized the Empire and even let the Eastern half prosper for more than a millennia after the split.

letter a is the answer