What is the meaning of a stop line at a "STOP" sign?

A stop line at a "STOP" sign is a crucial marking that indicates where vehicles are required to stop when approaching the intersection. This line is positioned before the intersection and is typically painted on the road to provide a clear visual cue for drivers. When a vehicle reaches a stop line, it must come to a complete stop before the line, ensuring that drivers have a clear view of oncoming traffic and pedestrians, and can proceed safely once the intersection is clear.

This requirement helps maintain traffic order and enhances safety for all road users. While the other options suggest alternative interpretations of the stop line, the legal and safety-oriented purpose of the stop line is to enforce a mandatory stop, making it clear that stopping is not optional and that yielding is not sufficient in this context. Therefore, vehicles must stop before the line to comply with the traffic rules associated with a "STOP" sign.