Hlp me please.

Which statement accurately describes an accomplishment of Emperor Yangdi that helped bring the Chinese together as one people?

A.

He brought a patchwork of small kingdoms under one rule by rebuilding the army.

B.

He helped spread Buddhism throughout Mongolia and Southeast Asia.

C.

He built a vast network of canals for trade and communication, known as the Grand Canal.

D.

He convinced Marco Polo to share the technology of Western Europe with all regions of China.