The correct option is C Taking advantage of popular discontent with the provisional government and promising to fulfill radical demands, the communists staged a successful armed revolution.
The provisional government didn't fulfil the radical demands of the people. A group of workers' organisations disapproved of the newly formed provisional government. Bolshevik leader Vladimir Lenin also joined this movement. He argued that the revolution would be pointless if the power weren't transferred to the workers' organisations, that is, the Soviets.
The demands were to withdraw Russia from the World War, to transform factories into public property, and to redistribute all the land equally among the farmers.