​What Was the Chief Reason for Migration of Peoples in North

Multiple Choice

​What was the chief reason for migration of peoples in North Africa to go east and south to resettle?

A) ​Invasion by Egyptians.
B) ​Warfare among tribes in the the Sahalian kingdoms.
C) ​Egyptians dammed the Nile river and made settled agriculture impossible.
D) ​Drying up of the Saharan grasslands.
E) ​Trade connections with the Indian ocean network.