What is powered by the hydraulic system concerning landing gear?

The correct answer indicates that nose wheel steering is powered by the hydraulic system in the context of landing gear operations. In many aircraft designs, particularly those that incorporate more advanced landing gear systems, the nose wheel steering mechanism is often hydraulically actuated. This allows for more responsive and precise control during taxiing, takeoff, and landing.

By using hydraulic power, the system can provide greater force and smoother operation than mechanical linkage alone. This is particularly important in larger aircraft, which require more robust systems to manage the dynamics during ground operations. The hydraulic system allows pilots to achieve effective directional control without requiring excessive physical effort.

The other options do not accurately represent systems typically powered by the hydraulic system. Main gear steering is generally controlled using the aircraft's ailerons and rudder rather than hydraulics. Flaps, while they can be powered by hydraulics, are a separate system from landing gear steering and do not fall under the same category. Tail wheel operation, depending on the aircraft, may involve different mechanisms that are not specifically related to hydraulic power in the same way as nose wheel steering.