After the War, Why Did National Governments Quickly Establish Authority

After the war, why did national governments quickly establish authority over questions of guilt and punishment for those who had collaborated with the Nazi regime?

A) Governments wanted to turn attention away from the issue of collaboration.
B) Unofficial groups were seizing and executing alleged collaborators on their own.
C) Many Nazi collaborators were fleeing to South America.
D) Governments wanted to prevent the possibility of rebellion by a Nazi underground.