Final answer:
The Munich Agreement in 1938 is the best example of the appeasement policy followed by Britain and France prior to World War II.
Step-by-step explanation:
The best example of appeasement policy followed by Britain and France prior to the start of World War II was the Munich Agreement in 1938. In an attempt to avoid war, British Prime Minister Neville Chamberlain and French Premier Édouard Daladier agreed to allow Germany to annex the Sudetenland in Czechoslovakia. They believed that giving in to Hitler's demands would prevent further aggression. However, this policy of appeasement ultimately failed as Hitler continued to expand his territory, leading to the beginning of World War II.