How Did the Bolshevik Revolution in Russia in 1917 Change

How did the Bolshevik Revolution in Russia in 1917 change the course of the war?

A) Germany's own people began to revolt, leading to a weakening of the axis powers, giving the Allies an advantage.
B) The Polish people in Germany revolted, distracting German forces from fighting France and Britain and giving the Allies an advantage.
C) Socialists in the United States refused to help with the war effort, inhibiting U.S. involvement and prolonging the war.
D) Russia dropped out of the war, so Germany could concentrate on fighting in the west.
E) Russia renewed attacks on Germany from the east, so that Germany began to weaken, from fighting on both fronts.