Prior to the presence of Europeans, the slave trade in Africa took place both internally and along the great Indian Ocean.
Option C.
Step-by-step explanation:
The slave trade along this Trans Saharan and Indian Ocean Region dates back to 8th century. Most of the slaves were traded in Arab for the purpose of household duty, though were subjected to all forms of torture about which, all of us know.
The slave trade also was common internally in the Africa where military soldiers of the defeated army and weak clan members were captured and made slaves.