Question

What event happened after the Qin Dynasty collapsed? Lu Bang abandoned Legalism. Wu Di appointed his grandson emperor. A civil war broke out. The Great Wall was completed.

Answer 1

Since the Qin Dynasty was the first imperial dynasty in China, the best option from the list would be "A civil war broke out", since there was a large power vacuum to be filled.

Answer 2

I believe the answer is:  "A civil war broke out"

When the qin dinasty collapes, several groups in china started to arise and tried to take control over the highest power in the govenrment. Most of them came from the residual of several empires that Qin conquered during the seven warring states period.