What does a solid red traffic light indicate?

A solid red traffic light clearly indicates that drivers must come to a complete stop at the intersection or traffic signal. This rule is critical for maintaining safety on the roads, as it helps control the flow of traffic and prevents accidents. When the light is red, no vehicles should proceed unless there is a specific signal or sign permitting them to do so, such as a right turn on red after a complete stop, and only if it is safe to do so.

The other options do not apply in this scenario. "Go" suggests an action that contradicts the instruction of a red light, while "Yield" implies giving way to other traffic, which is not relevant when facing a red signal. "Caution" suggests a warning to be prepared for potential changes in traffic conditions, which is not the direct instruction given by a solid red light. Thus, the instruction to stop is essential for ensuring safety and order on the roads.