Airplanes were vital for ww1 to ease transport of amo and soon guns on the planes including bombs this made it easier for to launch quick air strikes on places like bases vulnerable to air strikes
Your answer is A. Hope I helped.
A key advantage was that the Soviet Union had been damaged by the Nazis invasion of their country and by the deaths of over 20 million people fighting them so it was weakened by the war unlike the US which had only suffered at Pearl Harbour but not in the mainland USA.