What does a flashing red light signal at an intersection?

Answer: B — Stop and proceed when safe

A flashing red light at an intersection signals that drivers must come to a complete stop, similar to a stop sign. After stopping, drivers are required to yield to any vehicles or pedestrians that may be in or approaching the intersection, and may only proceed when it is safe to do so. This ensures that traffic is managed effectively and safely, minimizing the risk of accidents. The other choices suggest different actions that do not align with the standard traffic rules regarding flashing red lights. For instance, proceeding without stopping or only stopping if other cars are present could lead to unsafe situations and conflicts, as it disregards the requirement to stop and assess the intersection thoroughly.