ANS:D - all (a), (b) & (c).

The correct answer is: all (a), (b) & (c). Explanation:

1. Throttle down (i.e., reduce) the pressure of steam: Nozzles in steam turbines are often designed to accelerate steam flow while simultaneously reducing its pressure. This process helps in efficiently converting the thermal energy of the steam into mechanical energy, which can be used to drive the turbine.
2. Convert internal energy into kinetic energy: As steam passes through the nozzle, the pressure energy of the steam is converted into kinetic energy. This increase in kinetic energy is essential for driving the turbine blades and generating mechanical work.
3. Increase the velocity of steam: Nozzles work by accelerating the flow of steam, which increases its velocity. This high-velocity steam is directed onto the turbine blades, causing them to rotate and thus driving the turbine.