Step-by-step explanation:
The event that resulted in the United States ending its policy of neutrality in World War II was A. the attack on Pearl Harbor. On December 7, 1941, Japanese forces launched a surprise attack on the United States naval base at Pearl Harbor, Hawaii, which resulted in the deaths of more than 2,400 Americans and the destruction of numerous ships and aircraft. The attack led the United States to declare war on Japan and enter World War II on the side of the Allies.