Which of the following colors indicates a traffic stop sign?

The color red is universally recognized as a signal for drivers to stop. This is why red is used for traffic stop signs, as it is highly visible and conveys a sense of urgency, indicating that a vehicle must come to a complete stop at the intersection or location indicated by the sign. The prominence of the color red in the context of signaling danger or the need to halt is effective in catching a driver's attention, enhancing road safety. Other colors like green indicate go or safe passage, yellow signifies caution, and black is generally used for regulatory signs or background elements, but none of these convey the immediate action to stop as effectively as red does.