Here were the choices on that question:
a. poverty
b. lack of adequate rivers
c. mountains
<span>d. richness
The answer is D. richness. Based on A Companion to World History, the African Sahel can be a corridor of communication between Nile and Niger valleys but did not materialize. The reason was the richness of Sahel that it that it can provide for itself even without trade.
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It is the mongols, this answer is
