Answer:
A. Very few Roman emperors in the centuries after Augustus were competent rulers; most were insane, greedy, or both.
B. Exposure to diseases from other lands killed many Romans.
The fall of the Roman Empire was a very slow process, and one that occurred due to many contributing factors. One of the most important reasons for it was the fact that many Roman emperors during this time period were not competent rulers. Therefore, they were unable to face the challenges of the new Barbarian kingdoms. Additionally, exposure to diseases from other areas killed many Romans, further weakening the empire.