Which event contributed to the u. s. entry into world war i?

Germany's resumption of submarine attacks on passenger and merchant ships in 1917 became the primary motivation behind Wilson's decision to lead the United States into World War I.

Explanation:

The U.S. 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

Explanation:

letter a is the answer