What are three types of commonly used flight control systems?

In the context of flight control systems, cable, push-pull, and torque tubes are indeed common methods used to connect the pilot's input to the control surfaces of an aircraft.

Cable systems utilize flexible cables that transmit control movements, which is an effective and lightweight method widely used in general aviation. Push-pull systems involve rods that can move in linear motion to operate control surfaces, providing a direct mechanical linkage. Torque tubes refer to systems where a rigid tube transfers rotational motion, converting the pilot's inputs into the necessary movement for altering flight control surfaces.

The other options each present at least one component that is less typical in conventional flight control applications. For instance, pneumatic systems, while they can be used in some specific aircraft for other applications, are not commonly employed in primary flight control mechanisms as compared to the other listed methods. Similarly, while hydraulic systems are prevalent in larger aircraft for more powerful control, they do not fit into the combination provided in the selected answer, which focuses on more traditional mechanical connections.