The Entry of the United States into World War I

The entry of the United States into World War I in April 1917

A) gave their nearly-defeated allies a psychological boost.
B) was greatly feared by the German naval staff.
C) was a response to Turkey's entrance into the war on the side of the Central Powers.
D) put an end to Germany's use of unlimited submarine warfare.
E) was an attempt to keep Russia in the war after the February Revolution.