In the operation of a marine propulsion gas turbine, kinetic and thermal energy required to drive the main propeller shaft are extracted by the _________.

Correct Answer: Option D — power turbine

The power turbine is specifically designed to extract the remaining thermal and kinetic energy from the exhaust gas stream after it leaves the gas generator. This extracted energy is converted into mechanical torque, which is then transmitted through the reduction gear to drive the vessel's main propulsion shaft.