As what the map shows, one of the geographical features of West Africa is the Sahara Desert. Sahara Desert is the largest hot desert in the world. Camel caravans are important innovation in trade in West Africa because camels are the only animals that can withstand the hot temperature of the desert while carrying goods, and without food and water. The fat in the camels' humps gave them the energy to walk the desert even without food and water. The camel caravans made the West - North Africa trade possible, establishing trade routes across the hot desert.
I think the best answer from the choices listed above is option D. It is at dry that physical weathering most likely to happen. Hope this answers the question. Have a nice day.
