When are you allowed to use high beam headlights?

Answer: C — When there are no oncoming vehicles.

Using high beam headlights is appropriate when there are no oncoming vehicles. High beams provide better visibility at greater distances, which is particularly beneficial on dark roads. However, they can dazzle and impair the vision of other drivers if used improperly, particularly when other vehicles are approaching. Maintaining safe driving practices includes being considerate of other road users; therefore, using high beams only when the road is clear ensures that visibility is maximized without compromising the safety of others. In terms of the other options, high beam headlights are not advisable in foggy conditions, as the light reflects off the fog and can reduce visibility. They are also not typically used in populated areas where streetlights provide illumination, making high beams unnecessary. Using them at all times would disregard the safety of others and can lead to dangerous driving situations.