When must you use your headlights?

Using your headlights during specific conditions is crucial for ensuring safety on the road. It's important to illuminate the area ahead and increase your visibility to other drivers. Headlights should be used from sunset to sunrise, as darkness significantly reduces visibility. Additionally, in conditions like rain, snow, or fog, using headlights is essential because these weather conditions can create low visibility scenarios.

Therefore, using headlights during both nighttime hours and adverse weather conditions is necessary. It not only helps you see the road better but also allows other drivers to see you, reducing the risk of accidents. This is why the correct answer encompasses both scenarios.