How does the autopilot respond if the speed command wheel is rotated?

The correct response is that the autopilot adjusts the airspeed accordingly when the speed command wheel is rotated. This function is crucial for a pilot, as it allows for active management of the aircraft's speed without the need to manually inputs changes into the throttle.

When the speed command wheel is manipulated, it communicates the desired airspeed to the autopilot, which then calculates the necessary throttle adjustments to maintain that selected speed, thus ensuring that the aircraft operates within the desired parameters for efficiency and safety during flight. This feature is particularly relevant during varied flight phases, such as climb or descent, where maintaining a specific airspeed is vital.

The other options do not accurately describe the system's behavior in response to changes in the speed command wheel. The autopilot won't disengage all commands or only engage in speed mode, nor will it exclusively adjust vertical speed. Instead, its operation is centered on maintaining the selected airspeed in conjunction with other flight parameters.