Question

What caused the United States to break its neutrality and enter World War I?
a.It had signed a treaty of alliance with England in 1902.
b.The Germans were sinking its supply ships heading for France and England.
c.The Germans invaded Belgium, angering nations internationally.
d.The Archduke of Austria was assassinated.

Answer 1

What ultimately brought the US out of its neutrality was when the Germans wanted to stop supplies from getting to Great Britain from the US. So, they sunk the supply ships which also had hundreds of Americans on board which the Germans killed altogether (triggering their anger and causing them to join the war).