Which of the following situations would require you to use your headlights?

Using headlights during foggy conditions is essential for safe driving. Fog can significantly reduce visibility, often to the point where distinguishing objects and other vehicles becomes challenging. In such conditions, low beam headlights are particularly effective as they illuminate the road immediately in front of the vehicle without reflecting too much light back into the driver's eyes, which can happen with high beams.

The other situations presented do not necessitate the use of headlights in the same way. Driving during bright daylight usually does not require headlights, as natural light is sufficient for visibility. On clear and dry roads, well-lit roads typically make headlights unnecessary during the day. Lastly, the urgency to arrive somewhere does not influence the requirement to use headlights; safety should always take precedence over speed, regardless of the conditions. Therefore, in fog, using headlights is critical to ensure your own visibility and that of other drivers on the road.