The correct answer is C.
The Selective Training ans Service Act of 1940 required all men between the ages of 21 to 45 to register for the draft. This was the first peacetime draft in U.S. history. The draft was done by lottery and if selected, the men had to served at least one year in armed forces.
At that time the United War was not at war, but many people believed that the country would be eventually drawn into it. With the fall of France to the Nazis in June 1940, Americans were growing uneasy about Great Britain's ability to defend Germany on its own. National polls showed a growing majority in favor of instituting a draft.