Hello. You did not provide the answer options, nor did you say which empire the question refers to, which makes it impossible for that question to be answered accurately. However, I will try to help you in the best possible way.
One of the main economic reasons for the fall of the empires was the increase in inflammation and the decrease in trade. As the empires were established mainly through trade, the limitation of trade led to a high rate of unemployment and need among citizens. moreover, this inflation led to the limitation of resources such as gold, silver and bronze, which diminished economic power and weakened the empire.