Answer:
Julius Caesar's defeat by Carthage in the Third Punic War cost Rome most of its overseas possessions
Waves of smallpox, plague, and other diseases brought to Rome from foreign lands ravaged the city
Step-by-step explanation:
There were various reasons the Roman Empire fell and some of them include their military overexpansion, reliance on slaves and mercenaries, corruption, arrival of new religion, various diseases, etc.
Based on the given options, the correct answers are the defeat at Carthage during the Third Punic War cost them a lot, and waves of smallpox diseases and other diseases.