I remember this, it's C. Years of dust storms in the Midwest in the 1930s. That's over here in Texas where I live it happened, but more west and south. The massive dust in the area filled people's houses, damaged crop areas, and many people were left homeless. Some moved to areas where that phenomenon didn't happen. All of this was caused by drought which caused high winds to blow the soil everywhere throughout different states. I believe it was a whole decade until all of it stopped.
