The correct answer is B) The Russian government was weakened and eventually overthrown in a revolution.
During World War I, the Russian Empire was a vast empire based in an agricultural economy with a large poor population. The worker masses, led by Vladimir Lenin and the Communist party, organized in Soviets (councils) and following the Marxist precepts started a revolutionary movement that overthrown the Imperial government in October 1917 and established the first Communist government under the name of Union of Soviet Socialist Republics. As a result of this, Russia left the war.