What does a red light indicate at a traffic signal?

A red light at a traffic signal universally indicates that drivers must come to a complete stop and wait for the green light before proceeding. This rule is crucial for ensuring safety at intersections, as it prevents collisions between vehicles and pedestrians. When a driver encounters a red light, it is their responsibility to halt their vehicle behind the stop line or crosswalk and remain stopped until the signal changes to green. This action allows other vehicles, especially those traveling in the opposite direction or those with the green light, to proceed safely.

The other choices do not align with traffic regulations; yielding to oncoming vehicles might suggest a need to let others through inappropriately, proceeding with caution misinterprets the clear stop requirement, and only stopping if no other cars are present undermines the necessity of adhering to the signal indiscriminately. Thus, understanding the importance of a red light as a mandatory stop helps maintain order and safety on the road.