What caused the United States to enter World War I after three years of neutrality?

(1 point)
Responses

Germans attacked Pearl Harbor.
Germans attacked Pearl Harbor.

Germans treated prisoners of war harshly.
Germans treated prisoners of war harshly.

German submarines sank U.S. merchant ships.
German submarines sank U.S. merchant ships.

Germans were close to developing an atomic bomb.

German submarines sank U.S. merchant ships.