When must headlights be used during the day?

Answer: B — When visibility is reduced due to weather conditions

Headlights must be used during the day when visibility is reduced due to weather conditions such as rain, fog, snow, or other impairing elements. This is an essential safety measure to ensure that your vehicle is visible to others on the road, enhancing safety for both yourself and other drivers. Many accidents occur because vehicles are not easily seen in poor visibility, making it crucial to have your headlights on in such conditions, even if it is daytime. This practice is often mandated by law in various jurisdictions to promote safer driving practices. Using headlights only at night or strictly at sunset limits their important function during times when visibility drops. Additionally, while headlights are necessary in tunnels, the need extends beyond that specific scenario to encompass a variety of circumstances where driving visibility can be compromised.