Which mechanism is responsible for activating the anti-skid system during maximum braking?

The correct answer is the wheel and tire assemblies, as they play a crucial role in the operation of the anti-skid system during maximum braking. When an aircraft brakes, the wheel speed is monitored through the wheel and tire assemblies. If the system detects that a wheel is about to skid or lock up due to excessive braking force, it activates the anti-skid system to modulate brake pressure accordingly. This modulation prevents wheel skidding and maintains tire contact with the runway, thereby improving braking performance and safety.

The function of flight control surfaces is unrelated to braking systems; they are primarily responsible for controlling the aircraft's attitude and direction in flight. Pressure sensors in the wheels do contribute to the overall monitoring system, but they relay information rather than activate or directly control the anti-skid mechanism. Hydraulic fluid levels are critical for overall hydraulic system function but do not directly trigger the anti-skid system action during braking scenarios. Thus, the wheel and tire assemblies are central to the proper operation of the anti-skid system, especially under conditions of maximum braking.