How many reflectors must every trailer have on the rear?

Answer: B — Two

Every trailer must have two reflectors on the rear to ensure visibility and safety, especially during low-light conditions. This requirement helps to alert other drivers of the trailer's presence from various angles and distances, significantly reducing the risk of accidents. Having two reflectors provides redundancy, allowing for effective signaling no matter the vehicle's position and enhancing the visibility of the trailer, which is particularly crucial given that larger trailers can be more difficult to see compared to standard vehicles. The placement and number of reflectors follow regulations designed to enhance road safety, emphasizing the importance of proper markings on vehicles that are often on the road alongside passenger cars.