When visibility is substantially reduced, what is required regarding headlight usage?

Using low-beam headlights in conditions of substantially reduced visibility is essential for safe driving. Low-beam headlights provide adequate illumination of the road directly in front of the vehicle while minimizing glare for oncoming drivers. This is particularly important in situations such as fog, heavy rain, or snow, where high beams can reflect off moisture in the air and create a blinding effect, further reducing visibility.

Utilizing low beams allows drivers not only to see better but also to be seen by other road users, which enhances overall safety. This practice aligns with traffic regulations in many areas, promoting responsible and safe driving behaviors under adverse conditions.

In contrast, the other options are not suitable for use in reduced visibility. High beams can actually worsen visibility in fog, heavy rain, or snow. Parking lights are insufficient for safe travel, as they do not provide the necessary illumination for driving. Additionally, headlights are required for safe navigation in reduced visibility situations, making it critical to use them appropriately.