Why was World War II a defining event in the history of the 20th century ?

A. It brought unprecedented destruction and loss of life, thereby putting into question the entirecultural and political legacy of Western civilization.
B. It was followed by Soviet domination of Eastern Europe and by the entrenchment of the Soviet totalitarian system of rule.
C. It was followed by the Cold War, which affected international politics throughout the world.
D. All of these answers