How did the Selective Service Act of 1917 contribute to the war effort?

A.
It allowed the federal government to expand the military through the draft.
B.
It created an alliance with other countries to strengthen forces against Germany.
C.
It protected the war effort from disloyal European immigrants living in the US.
D.
It expanded crimes for any expression of disloyalty or contempt to the US military.

A. It allowed the federal government to expand the military through the draft.