Questions: Which event most clearly influenced the U.S. decision to enter World War I on the Allied side? Germany sunk the Lusitania, causing 128 American deaths. Britain and France were members of the Triple Entente. Germany decided to end U-boat attacks on commercial ships. Britain imposed an embargo on Germany that created terrible hardship among German civilians.

The answer is Germany sunk the Lusitania, causing 128 American deaths.

The sinking of the Lusitania in 1915 by a German U-boat was a significant event that influenced American public opinion and increased tensions between the United States and Germany. The loss of 128 American lives in this attack was a major factor that contributed to the U.S. decision to enter the war on the side of the Allies. It highlighted the dangers of unrestricted submarine warfare and the threat it posed to American lives and interests.

While the U.S. had cultural and economic ties with Britain and France, the fact that they were members of the Triple Entente was not the most direct reason for the U.S. entering the war. The U.S. initially maintained a policy of neutrality and was more influenced by direct threats to its citizens and interests.

This option is incorrect because Germany's decision to end U-boat attacks would have been a move towards de-escalation, not a reason for the U.S. to enter the war. In fact, it was Germany's resumption of unrestricted submarine warfare in 1917 that further provoked the U.S. to join the conflict.

While the British blockade did create significant hardship in Germany, it was not a direct factor influencing the U.S. decision to enter the war. The U.S. was more concerned with actions that directly affected its own citizens and interests, such as the sinking of the Lusitania and the Zimmermann Telegram.