The answer is: A. Sahara
Crops need several crucial things in order to live, including water, nutritious soil , and sunlight.
Sahara wouldn't be able to provide enough water ( since the high temperature make water evaporated quickly) and nutritious soil for the plants, (Sahara is consist of non-nutritious sands).
You can still grow quite a lot of crops on Rain forest, Savanna , and Sahel. Tropical fruits grow really well in rain forest, sahel is good for peanuts and peas , and Savanna can be used to grow corns and millet.
