When must headlights be turned on during the day?

The correct response indicates that headlights must be turned on whenever visibility is less than 150 meters. This rule is based on ensuring safety on the road during conditions where visibility is significantly compromised, such as in heavy rain, fog, or other adverse weather situations. Visibility under 150 meters can hinder a driver's ability to see other vehicles, pedestrians, and road signs, thus increasing the risk of accidents.

In contrast, headlights are not strictly required only during foggy conditions, as described in the first option; rather, they must be used whenever visibility drops below the specified distance. While the third option suggests that headlights should be on during daylight hours in urban zones, this is not a standard requirement and can vary by jurisdiction. Similarly, the fourth option implies that headlights are always needed in rural areas, which is not the case; the requirement is dependent on visibility conditions rather than the location type. Therefore, recognizing the importance of headlights in maintaining safety during low visibility periods is essential for all drivers.