Between march and october of 1917, russia's provisional government was made up of

members of the middle class.

members of the communist party.

members of the working class.

members of the revolutionary forces.

The answer that best fits the blank provided above is the first option: MEMBERS OF THE MIDDLE CLASS. These are the people who belong in between the upper class and the working class, or typically, those who are in the middle of the social hierarchy. The middle class mostly comprise the larger population in the society.