(A) 1910
(B) ** 1917
(C) 1918
(D) 1920
EXPLANATIONS BELOW
Concept note-1: -On April 4, 1917, the U.S. Senate voted in support of the measure to declare war on Germany. The House concurred two days later. The United States later declared war on German ally Austria-Hungary on December 7, 1917.
Concept note-2: -The US entered World War I because Germany embarked on a deadly gamble. Germany sank many American merchant ships around the British Isles which prompted the American entry into the war.
Concept note-3: -Along with news of the Zimmermann telegram threatening an alliance between Germany and Mexico against America, Wilson asked Congress for a declaration of war against Germany. The United States officially entered the conflict on April 6, 1917.
Concept note-4: -These events finally brought the U.S. into the war on the side of the Allies on April 6, 1917. In the months that followed, over four million Americans of all backgrounds entered military service and prepared to go overseas.
Concept note-5: -U.S. Enters World War I On April 6, 1917, the United States formally declared war against Germany and entered the conflict in Europe.