What happened during the Russian Revolution?

A.
Mikhail Gorbachev instituted social and political reforms.
B.
The Soviet Union was dissolved into 15 independent nations.
C.
Vladimir Lenin and the communists overthrew the Russian tsar.
D.
Joseph Stalin made widespread cultural and economic changes.

Please select the best answer from the choices provided.

C. Vladimir Lenin and the communists overthrew the Russian tsar.