Which of the following reflects a requirement for lights and reflectors on a vehicle?

The requirement for lights and reflectors on a vehicle is critical for safety and visibility. Clearance lights, which are designed to make a vehicle more visible on the road, must comply with specific color regulations.

The stipulation that clearance lights on the rear should be red is grounded in safety standards. Red lights are universally recognized as signaling caution or danger, which is essential for vehicles to warn others when they are approaching from behind. This color coding enhances the visibility of vehicles, particularly at night or in low-visibility conditions, ensuring that other drivers can easily identify the vehicle's dimensions and position on the road.

In contrast, the requirement that all clearance lights must be amber highlights the need for these lights to indicate the vehicle's presence to oncoming traffic and those in its vicinity. Therefore, while amber lights serve a critical function, the rear clearance lights specifically being red is what solidifies their role in the context of signaling and safety.

Other options that suggest only certain colors or eliminate the need for lights on the sides do not align with the established safety standards for commercial vehicles, rendering them incorrect.