Prior to the beginning of World War I, many European nations took an imperialistic approach to Africa and began colonizing it. Why did they do this?

A. They were trying to prevent African nations from gaining their freedom.

B. Their economies were becoming stagnant, and they needed a new source of trade.

C. Each needed a base of operations knowing that another war was coming.

D. There was a need for keeping the United States from colonizing the continent.