Operation Barbarossa was postponed by five weeks because
a. there were unexpected production delays.
b. Germany decided to protect its flank in the Balkans.
c. negotiations with the Soviet Union were still in progress.
d. Stalin knew the original date of attack, March 15, 1941, and was prepared.
e. the new date June 21, 1941 was the eve of the first anniversary of France's capitulation.