Final answer:
The sinking of the Lusitania, Unrestricted submarine warfare, and The Zimmerman Telegram pushed the U.S. into World War I.
Step-by-step explanation:
America's entry into World War I was influenced by several actions and events. The sinking of the Lusitania in 1915, a British passenger ship that was sunk by a German submarine, killed American citizens and created public outcry. Unrestricted submarine warfare by Germany, in which they attacked ships without warning, also contributed to the U.S. becoming involved. Additionally, The Zimmerman Telegram, a message sent by Germany to Mexico proposing an alliance against the U.S., further pushed the U.S. towards war.
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