Mansa Musa's net worth today is about $400 Billion.
An example of Social Darwinism would be "Survival of the Fittest". Those who are the strongest will survive.
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I think the answer is D)the U.S constitution
This was the time when Islam started spreading through Africa and those who resisted it and fought wars against Islamic conquerors would be enslaved and sold. Europeans also started participating in this slave trade and would buy numerous slaves from the Arabs who would enslave their prisoners of war and who often traded with Europeans.