In a sense (BLANK) is responsible for the abundant food in america's so called "bread basket" as well as decre?

I'm pretty certain that they were looking for D.) Climate Change. Desertification is the cause of decreased food production in Northern Africa and glaciation (and the following melting) is the cause of the nutrient rich soils of America's "bread basket" which has lead to the abundance of food there. Both of these things occured as a result of climate change. Fluvial erosion refers to erosion along a river or stream bed and is irrelevant to the question.