Final answer:
Vehicles must have at least two functioning headlights and taillights to ensure visibility and safety during poor lighting conditions.
Step-by-step explanation:
When visibility conditions warrant, vehicles and equipment shall be equipped with at least two functional headlights and taillights. This ensures that there is sufficient lighting for the vehicle to be seen by other drivers, as well as for the driver to see the road ahead and communicate the vehicle's presence and intentions. In the context of vehicle lighting systems, headlights and taillights are fundamental safety features designed to maintain visibility under poor light conditions. Headlights typically work in pairs to provide a balanced and effective beam of light that illuminates the road ahead, while taillights signal the vehicle's presence from the rear.