Why were the Balkan countries of southeastern Europe key to Hitler's invasion plan of the
USSR:

Why where the Balkan countries of South Eastern Europe key to Hitler's invasion plan of the USSR? Hitler wanted to build bases in south eastern Europe for the attack on the Soviet union. He also wanted to make sure that the British did not interfere.

Explanation:

Hitler wanted to build bases in south eastern Europe for the attack on Soviet Union

i think the answer is b.

a memoir is the correct answer