Which of the following is an accurate example of how civilizations were impacted by physical geography?

A. The government and religions of Southeast Asia were similar to Euresia, because it was connected by rivers.

B. The Swahili in Africa were exposed to Christianity by Arab traders due to the trade winds of the Indian Ocean.

C. North and south China were united throughout history because of the lack of physical barriers.

D. The Saharan desert was a physical boundary that isolated north and south Africa from one another.