What is the function of a traffic light's yellow light?

The function of a traffic light's yellow light is to serve as a warning that the light will soon change to red. This indicates to drivers that they should prepare to stop if it is safe to do so, promoting safety and reducing the likelihood of accidents at intersections. The yellow light acts as a transition period, giving vehicles and pedestrians the necessary time to react to the upcoming change in traffic conditions.

The other options do not accurately reflect the purpose of the yellow light. For instance, the yellow light does not indicate a pedestrian crossing, as pedestrian signals are typically separate from traffic lights. Additionally, the yellow light does not invite vehicles to accelerate; rather, it is a caution to slow down. Finally, while the yellow light does signify a change in the traffic cycle, its primary purpose is to alert drivers to the impending red light, rather than merely signaling the end of the cycle. Understanding the role of the yellow light is crucial for safe driving practices at traffic signals.