What caused the Golden Age of China"?

The 3rd option

Explanation:

I found The golden age of China was "golden" because many important inventions and advancements were made. The Song dynasty improved the government by hiring based on merit. New technology with irrigation improved food cultivation and created food surpluses. So I'm thinking the answer is the 3rd option.

hope this helps.

answer; adjusting and adapting to a culture other than one's own;