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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According to the Wikipedia, more than 75% of the worlds most active volcanoes occur on the Ring of Fire.
About 81% - 90% of the words largest earthquakes also occur on the Ring of Fire.
