How many red reflex reflectors must vehicles have on the rear?

Answer: B — Two

Vehicles must have two red reflex reflectors on the rear to enhance visibility and safety. These reflectors are crucial for signaling the presence of the vehicle to others, especially in low-light conditions. The requirement for two reflectors allows for better visibility from different angles, ensuring that drivers approaching from various directions can see them clearly. This regulation helps reduce the risk of rear-end collisions and other accidents that could occur if a vehicle is not easily noticeable. Having only one reflector could limit the angles from which a vehicle can be seen, increasing the chances of accidents. Therefore, having two red reflex reflectors is essential for maintaining safety on the road.