What color must reflective triangles be in order to be considered valid emergency equipment?

Answer: D — Red

Reflective triangles must be red in order to be considered valid emergency equipment. This specification is crucial for ensuring that the triangles are highly visible to other drivers, especially in low-light conditions or inclement weather. The red color stands out against most backgrounds, making it easier for approaching vehicles to see the warning signal and react appropriately. The use of red is standardized and widely recognized as a warning color, contributing to road safety during emergency situations. Such visibility is essential for protecting the driver and minimizing the risk of accidents on the road.