Which of the following best describes a ‘stop line’ marking?

The description of a 'stop line' marking is accurately captured by stating that it is a line where vehicles must stop when required by law. This marking is typically painted on the road surface at intersections and pedestrian crossings. Its primary purpose is to indicate the point at which drivers must bring their vehicles to a complete stop to comply with traffic regulations, particularly at traffic signals or stop signs. This ensures the safety of pedestrians and other road users by creating a clear stopping point.

In contrast, other options describe different types of markings. A speed limit designation relates to a regulation on how fast a vehicle may travel, while lane separation lines help organize traffic flow by designating distinct paths for different directions of travel. Temporary markings are used to guide traffic in construction zones but do not serve the specific function of directing a stop.