What contributed to the beginning of the decline of the Roman Empire?
Choose all answer that are correct.

A: The soldiers hired on the frontiers were not willing to go defend other parts of the empire.

B: Incompetent rulers placed huge tax burdens on the Roman citizens.

C: Regardless of the strength of the emperors, the Roman army was unable to hold back barbarian invasions from the south and west.

D: Soldiers in the outer parts of the Roman Empire often supported local commanders instead of the emperor.