High speed protection is deactivated when:

High-speed protection is a critical function in the A320's flight control system that helps prevent the aircraft from exceeding its maximum operating speed (VMO). This protection feature is designed to automatically limit the aircraft's speed and maintain safe flight operations.

When the airspeed returns to VMO with the sidestick neutral, high-speed protection is deactivated because the aircraft is operating at a safe speed. At this point, the control laws can revert to normal mode, allowing the pilot to have full control without the limitations imposed by high-speed protection. This reactivation of normal control laws enables the pilot to maneuver the aircraft as needed, fostering a safer operational environment.

In contrast, other options do not directly address the conditions under which high-speed protection is disabled in an accurate manner. For example, simply pushing the stick forward may not guarantee that the aircraft is at a speed that allows for the deactivation of this protection. Reducing thrust levers to idle does not ensure the aircraft has returned to a safe speed either. Lastly, extending the speed brakes can slow the aircraft, but it does not necessarily bring it within safe operating limits if the airspeed is still above VMO. Hence, only the return to VMO with the sidestick neutral correctly