Which of the following contributed to the outbreak of the russian revolution in 1917?

There were two revolutions in Russia in 1917. In the first on, the February Revolution, the Czarist regime of Nicholas Romanov II was overthrown in favor of a Provisional Government. It was supposed to keep order until a Constituent Assembly could be elected to write a constitution.

The second one, the October Revolution, resulted in the overthrow of the Provisional Government, the dismissal of the Constituent Assembly and the takeover by Lenin and the Bolshevik Party. The Bolsheviks later took the name Communist Party and ruled until the dissolution of the Soviet Union.