Impulse Turbine:

• In impulse turbine, steam coming out at a very high velocity through the fixed nozzle strikes the blades fixed on the periphery of a rotor.
• The blades change the direction of the steam flow without changing its pressure.

• In an impulse reaction turbine, steam expands both in fixed and moving blades continuously as the steam passes over them. 

Hence, the correct option is (C).