What events might justify or not justify US entry to world war 1

Kennedy says that most historians agree that American entry into World War I tipped the scales against Germany and that without the participation of the United States the Allies would have lost, “defined as having to make a compromise peace with the Germans largely on German terms.” Things weren’t going well for the Allies by the spring of 1917. They had suffered a big setback in Italy, the French army faced a serious mutiny problem and Russia was teetering after the overthrow of the tsar, which would lead to the eventual loss of the Eastern Front.

the answer is b.india