What does a red traffic light indicate?

A red traffic light signifies that drivers must stop and remain stopped until the light turns green. This rule is crucial for maintaining safety on the road, as it helps prevent accidents by controlling the flow of traffic at intersections. When a red light is encountered, drivers are required to come to a complete stop at the designated line or before entering the intersection, ensuring they do not endanger themselves or others, including pedestrians and cross traffic.

Remaining stopped until the light changes to green ensures that vehicles will only proceed when it is safe to do so, allowing the traffic system to function smoothly and reducing the likelihood of collisions. This rule is universally recognized and enforced in traffic laws across many regions.

The other options do not align with the established traffic laws regarding a red light. For instance, proceeding with caution would imply that it's safe to move, which contradicts the requirement to stop. Yielding to pedestrians is also not sufficient; pedestrians have the right of way only when traffic signals allow for their safe crossing. Turning left only could lead to confusion about the appropriate action during a red light. Hence, the requirement to stop until the light turns green is the fundamental rule to follow.