What does it indicate if a traffic light turns yellow?

Answer: D — Both A and C

A yellow traffic light serves as an important warning signal to drivers. It indicates that the light is about to change to red, prompting the need for caution and readiness to stop. This is crucial because it helps ensure the safety of all road users, allowing for smoother traffic flow and reducing the likelihood of accidents. When the light turns yellow, drivers should prepare to stop, but they may also have to make a quick decision depending on their proximity to the intersection. If a driver is already too close to the intersection to safely stop, it is permissible to proceed with caution. Therefore, both preparing to stop and stopping only if it's safe to do so are valid responses to a yellow light, making this option the most comprehensive and accurate representation of what drivers should do when they encounter a yellow signal.