Appeasement was a popular policy because European leaders

wanted Hitler to be happy.

wanted to avoid another war.

knew that Hitler desired a confrontation.

had serious economic problems to deal with at home.

Explanation:

Appeasement is a strategy based on the moral conviction of fear of war that leads to adaption of non retaliative and non-aggressive stance  towards aggressors.

The most famous case of appeasement was the appeasement of Adolf Hitler by Prime Minister Chamberlain  in the late 1930's. The appeasement was due to the trauma of the first world war as the countries witnesses death of vast number of young people, due to this Britain opposed another war due to any circumstances. That is why it allowed Hitler to expand German territory.

B. on edge

Explanation:

increase in population