B. A group of people, say the Bolsheviks of Soviet Russia, overthrow the government. Although there was not a democratic government set up afterward, it is still a revolution.
The correct answer is - b. A group of people overthrow the monarch of their country and set up a democratic government.
When a big mass of people gather and they have a goal of overthrowing the monarch because they are not content of their living conditions under his/hers rule, and manage to do it in order to set a new government that will be democratic and will be serving the interests of the people, can be considered as a revolution. A nice example for this, but also a brutal one, is the Romania's case with the overthrowing of Ceausescu (who was murdered) in order to set up a democratic system and not allow the dictatorship to continue.
