The economics of most african colonies were dependent on

They were dependent on one or two crops.

One or two crops, is the right answer.

Explanation:

The colonial economy in Africa introduced as a due to the industrial revolution. The newly emerged industries of Europe required more raw material in order to make a profit. Therefore, to overcome this problem of raw material, the colonial economy was introduced in Africa. Such colonies were established to produce export-oriented crops. In the colonies of Africa one or two crops were grown that were sometimes cash crops.