What function does the seros in an autopilot perform?

In an autopilot system, the servo plays a crucial role in actuating control surfaces. Servos are responsible for converting electrical signals from the autopilot's control system into mechanical movement that positions the aircraft's control surfaces, such as ailerons, elevators, and rudders. This actuation is essential for maintaining the desired flight path as commanded by the autopilot, ensuring that the aircraft responds dynamically to changes in flight conditions or operational commands.

The other options involve functions that are either monitored or interpreted by the autopilot rather than directly acted upon. For example, navigation of the aircraft refers to determining the aircraft's position relative to its flight plan, while monitoring flight instruments involves assessing data from various aircraft systems. Providing altitude data pertains to sensors measuring altitude rather than the mechanism that achieves control surface movement. Thus, the servo's primary function in an autopilot is indeed to actuate control surfaces for maintaining flight stability and achieving specific flight maneuvers.