Which action should be taken to effectively reduce stopping distance in an emergency?

To effectively reduce stopping distance in an emergency situation, braking firmly is the most effective action. When a driver applies the brakes with sufficient force, it maximizes the vehicle's braking power and helps to bring the vehicle to a halt in the shortest possible distance. Firm braking activates the anti-lock braking system (if equipped) effectively, allowing the wheels to maintain traction and prevent skidding while the vehicle decelerates quickly.

Gradually applying the brakes can lead to a longer stopping distance, as it fails to utilize the full braking capability of the vehicle. Using the horn is not a method for reducing stopping distance; it serves as a warning signal to alert other drivers and pedestrians. Steering sharply might help in avoiding an obstacle but does not contribute to stopping distance, and it can potentially lead to loss of control. Therefore, braking firmly is crucial in an emergency to minimize stopping distance and ensure the safety of the vehicle occupants and others on the road.