How Did the Soviet Union Help Turn the Tide of War

How did the Soviet Union help turn the tide of war in Europe in 1942?

A) The Red Army forced Nazi troops to abandon their invasion of the Soviet Union and retreat westward toward Germany.
B) Stalin's forces invaded eastern Germany and captured Berlin.
C) The Soviet strategic air offensive on German cities and industrial centers broke resistance and facilitated an Allied invasion from the west.
D) The Red Army's occupation of the Balkans and Hungary cut Germany's access to oil and food supplies shipped through the Mediterranean Sea.