What Was Operation Barbarossa

What was Operation Barbarossa?

A) It was the German invasion of the Soviet Union, during which the scale of death of the war significantly increased.
B) It was the Allied invasion of France across the English Channel, during which their forces faced an Atlantic Wall built by the Nazis.
C) It was an undercover effort to liberate prisoners from German concentration camps.
D) It was a special German military "task force" of SS members that pursued Jews, Roma, homosexuals, the mentally handicapped, and Communists.
E) It was a large-scale secret project undertaken by British and American physicists to build the first atomic bomb.