Which of the following is a shared cause of the downfall for both the Han and Roman empires?

A. Both empires were split into three kingdoms.

B. Both empires grew too large to protect.

C. Both empires attempted to close the Silk Road.

D. Both empires were weakened by democratic protests

I think the correct answer from the choices listed above is option B. A shared cause of the downfall for both the Han and Roman empires would be that both empires grew too large to protect. The emperors had hard time securing their lands since they were too huge. Hope this answers the question.