The answer is A. a drought because during that time there was the Dust Bowl. The Dust Bowl was a time in America when there were massive dust storms which dirtied up any water.
It is not the Dust Bowl the Dust Bowl did not occur until the 1930s and it was called the Dirty thirties given that I would have to say and this is a guess can't give you a certainty yet I'm going to say it's C