(A) They attacked Germany on the eastern front.
(B) They had no significant effect on the fighting.
(C) They primarily provided training to British and French troops.
(D) ** They helped to push German forces back from their campaign towards Paris.
EXPLANATIONS BELOW
Concept note-1: -U.S. Neutrality The United States remained neutral at the beginning of the war. Individual Americans supported one side or the other, although the majority were sympathetic to the Allies. Many contributed to relief efforts; others volunteered as ambulance drivers or nurses, or even as pilots and soldiers.
Concept note-2: -Pershing, more than 2 million U.S. soldiers fought on battlefields in France. Many Americans were not in favor of the U.S. entering the war and wanted to remain neutral. However, the U.S. eventually did enter the war.
Concept note-3: -The American Expeditionary Forces arrived in Europe in 1917 and helped turn the tide in favor of Britain and France, leading to an Allied victory over Germany and Austria in November 1918. By the time of the armistice, more than four million Americans had served in the armed forces and 116, 708 had lost their lives.
Concept note-4: -The U.S. made its major contributions in terms of supplies, raw material, and money, starting in 1917. American soldiers under General of the Armies John Pershing, Commander-in-Chief of the American Expeditionary Force (AEF), arrived at the rate of 10, 000 men a day on the Western Front in the summer of 1918.