Choose the sentence in this excerpt that explains why United States involvement in World War I was significant.
A) By late spring 1918, however, hundreds of thousands of Americans arrived in Europe.
B) The bulk of the U.S. troops fought in their first major battle of the war, at Cantigny in France, in May 1918.
C) With the help of fresh U.S. troops, the Allies turned the tide against Germany on the Western Front.
D) By that fall, all the Central Powers sought an end to the conflict.
The correct answer is: C) With the help of fresh U.S. troops, the Allies turned the tide against Germany on the Western Front.
This sentence explains the significance of U.S. involvement in World War I because it highlights how the arrival of American troops provided much-needed support to the Allies, ultimately leading to a shift in the momentum of the war in their favor. This indicates that the U.S. played a crucial role in achieving victory and altering the course of the conflict.