When should headlights be dimmed?

Answer: B — When approaching another vehicle

Headlights should be dimmed when approaching another vehicle to prevent blinding or distracting the other driver. High beams can create a glare that is particularly problematic for oncoming drivers, making it difficult for them to see the road. By dimming headlights, you ensure a safer environment for all road users. This practice is an important aspect of responsible driving as it enhances nighttime safety for both you and others on the road. In other situations, like driving in fog, using high beams can actually reflect off the fog and reduce visibility, making it harder to see. In residential areas, while it's also common to use low beams, the primary reason for dimming, in this case, generally pertains to the presence of pedestrians and closely parked vehicles rather than approaching traffic. Lastly, when parking at night, headlights don't necessarily need to be dimmed since they should be off when the vehicle is parked.