I'm not sure if there's multiple choice for this question, but this is my answer.
The decline of the Roman Empire was caused by:
- the invasion of nomadic tribes, such as the Barbarians.
- economic instability.
- the rise of the Eastern Empire.
- over-expansion; the Romans had too much land to control and this is a big reason as to why they fell.
- government corruption and political instability.
- the arrival of the Huns.
- the spread of Christianity.
