How did world war i change after the united states became involved?

a.
the war was a stalemate before the united states became involved. after the united states became involved, the balance tipped to the allied powers.

b.
the war was fought with outdated weapons before the united states became involved. after the united states became involved, modern weapons were used.

c.
the war was fought in "no man's land" before the united states became involved. after the united states became involved, fighting moved to the trenches.

d.
the war was fought mostly in russia before the united states became involved. after the united states became involved, fighting moved to france.

A.  The war was a stalemate before the United States became involved. After the United States became involved, the balance tipped to the Allied powers

Explanation:

During World War I, the United States was the main supplier of food and armaments to France and England (members of the Triple Entente). With these exports, the US profited greatly. There were also investments and loans from US banks made to assist the Entente countries.

However, in order to receive the profits from the supply of arms and food, as well as to have a return on investment, the Entente needed to win the war. If England and France were defeated, US investments might not have a payoff, as debts would hardly be paid.

That was one of the main reasons that made the US effectively enter the First War alongside England and France to help them win, since until then the conflict had come to a standstill. The US presence was decisive for the victory of the Entente, as it took the Germans and Italians worn, after 3 years of war.