When should a driver dim their headlights when another vehicle is approaching at night?

Answer: D — 500 feet

A driver should dim their headlights when another vehicle is approaching at night to ensure the safety and visibility of all road users. The correct distance for dimming headlights is 500 feet. This distance is established to prevent blinding the oncoming driver with bright headlights, which can impair their vision and reaction time. By dimming the lights at this distance, the approaching driver can maintain proper visibility and avoid potential accidents. Choosing to dim headlights too late, such as at shorter distances, could lead to dangerous driving conditions, as it increases the likelihood of causing temporary blindness to the other driver. By adhering to the 500-foot guideline, drivers contribute to a safer driving environment for everyone on the road.