Which of the following components is crucial for the operation of a turboshaft engine?

In the operation of a turboshaft engine, all components mentioned play significant roles, making the correct choice comprehensive. The main rotor blades are essential as they translate the power generated by the engine into thrust or lift by interacting with the surrounding air. The fuel control unit manages the fuel flow to the engine, ensuring optimal combustion and performance, which is critical for maintaining the desired power output and engine efficiency. Lastly, the turbine wheel is a key component that extracts energy from the high-temperature, high-pressure gas produced by the combustor, converting it into mechanical energy that drives the main rotor blades. Each of these components is interdependent, making them all crucial for the proper functioning of a turboshaft engine. Therefore, recognizing that each component contributes to the overall operation underscores why "All of the above" is the correct answer.