What did a small car do at the red light?

The action taken by the small car at the red light is correctly identified as stopping. When a vehicle approaches a red light, it is typically required to come to a complete stop to ensure safety and comply with traffic regulations. Stopping at a red light is crucial to prevent accidents and allow pedestrian crossings.

The other actions, such as running the light, would imply disregarding the signal completely, which is unlawful and dangerous. Slowing down suggests a lack of commitment to stop, which is not recommended at a red light since drivers need to halt entirely before proceeding. Changing lanes at a red light may also lead to confusion and is generally not a safe maneuver when traffic is halted. Therefore, stopping is the appropriate and expected action in this scenario.