Final answer:
The US entered WWII due to the Japanese attack on Pearl Harbor, and the appeasement policy failed to prevent the war.
Explanation:
The primary cause of the US participation in World War II was the Japanese attack on the US naval base at Pearl Harbour. This event directly led to the United States entering the war.
An instance of the Anglo-French policy of Appeasement was seen when they allowed Hitler to take over part of Czechoslovakia in an attempt to avoid conflict, which ultimately failed to prevent World War II.
Learn more about Causes of US entry into WWII and the policy of Appeasement
