For which lighting condition must you always stop your vehicle?

When encountering solid red lights, flashing red lights, and blacked-out traffic signals, it is crucial to stop your vehicle. This is a fundamental traffic rule designed to ensure safety at intersections and maintain orderly traffic flow.

Solid red lights indicate that vehicles must come to a complete stop and wait until the light turns green, ensuring that they do not proceed when cross traffic may be moving. Flashing red lights function similarly to stop signs; they require drivers to stop and yield to all other traffic before proceeding. Blacked-out traffic signals signify that the light is not working, which also necessitates a complete stop as if it were a stop sign, to assess the intersection for any oncoming traffic.

The other lighting conditions listed do not universally require a complete stop. Solid green lights allow for continued movement unless otherwise impeded. Flashing yellow lights indicate caution, where drivers should slow down but are not required to stop. Flashing green lights typically indicate to drivers that they may proceed, often in a location with no immediate hazards. Thus, the correct answer captures the necessary action of stopping for safety in specific conditions where accidents are more likely without clear signals.