The Dust Bowl.
The farmers had overfarmed their land and had lost the valuable top soil. Take into consideration a drought as well, the high winds of the plains took the overfarmed (and dry) soil and blew it across the land.
Answer:
Truman believed that it was a necessity to drop the atomic bomb on Japan because he didn't want more Americans to die in this war. So C.
The immediate effect was that is spread information quickly and accurately, so it helped create a wider literate reading public.