When does the braking distance increase?

You selected both "When driving down slopes" and "When carrying heavy luggage." Both answers are correct. The braking distance increases when you drive downhill because gravity helps the vehicle gain speed, making it harder to stop. Carrying heavy luggage also increases braking distance since extra weight means more force is needed to bring the car to a stop. Headwind, however, does not increase braking distance; it can actually help slow the vehicle down slightly. Whenever you are driving with more weight or on a slope, always allow extra distance for braking for safety.