How did Southeast Asia’s geography contribute to the region’s economic development?

A.
Much of Southeast Asia is separated from the rest of Asia by high mountains, making it a difficult place to invade.

B.
Many Southeast Asian countries depended on their plentiful gold supply to make them wealthy.

C.
Some Southeast Asian countries commanded important waterways and controlled rich trade routes.

D.
Many Southeast Asian countries were easily accessible by monks and therefore adopted Buddhist culture.

C. Some Southeast Asian countries commanded important waterways and controlled rich trade routes.