What indicates that the Warrior PA-28A has reached an appropriate speed for takeoff?

The correct choice is determined by the fact that reaching the calculated takeoff speed is a critical factor for a successful takeoff in any aircraft, including the Warrior PA-28A. Takeoff speed is specifically calculated to ensure that the aircraft has sufficient lift to become airborne while maintaining control during the initial climb phase. It is based on the aircraft's weight, configuration, and operating conditions, providing a specific reference point for the pilot.

When the airspeed reaches this predetermined value, it indicates that the wings are generating enough lift to overcome the weight of the aircraft, allowing it to take off effectively. Monitoring the airspeed is essential during the takeoff roll, as it gives pilots a clear and measurable parameter to assess readiness for departure.

Although other options may seem relevant in certain contexts, they do not address the precise requirement for takeoff in the same way. For instance, the feeling of the aircraft being lighter is subjective and may vary from pilot to pilot, while the state of the control surfaces or having all instruments in the green does not directly relate to achieving the necessary airspeed for takeoff.