What is the law about using headlights in adverse weather?

The law requires that headlights be used in low-visibility conditions, such as during rain or snow, to ensure that drivers can see and be seen by others on the road. This recommendation is based on the fact that adverse weather can significantly reduce visibility, which can increase the risk of accidents. Using headlights in these conditions not only enhances the visibility of the vehicle but also helps illuminate the road for the driver, making it safer to navigate through difficult driving scenarios.

In contrast, stating that headlights must always be turned on might not take into consideration situations where visibility is adequate. Saying it is optional to use headlights does not emphasize the important safety measures required in poor weather. Finally, the option of only using daytime running lights fails to address the need for full headlights, which are necessary to improve visibility during severe weather conditions. Therefore, the correct understanding aligns with the requirement to use headlights specifically in low-visibility situations, making option B the most accurate choice.