Why Was Hitler Delayed in His Invasion of the Soviet

Why was Hitler delayed in his invasion of the Soviet Union in 1941?​

A) ​He was preoccupied with negotiating a tripartite Axis agreement with Japan.
B) ​He waited to see if the United States was going to enter the war.
C) ​He was required to assist Mussolini in his botched invasion of Greece.
D) ​He met with unexpected resistance in Vichy France.
E) ​He sought to position German forces in Iran and engage the USSR from the West and South.