Final answer:
The correct answer is D. headlights, which are crucial for visibility from dusk to dawn and are a legal requirement in many areas for driving at night.
Step-by-step explanation:
The correct answer is D. headlights. From dusk to dawn, it is essential to ensure that your headlights are always turned on when driving. This is not only a legal requirement in many areas but also a critical safety measure. Having your headlights on at night or when visibility is low due to weather conditions allows you to see the road ahead and helps other drivers see your vehicle. While other lighting systems on your car — such as brake lights, turn signals, and four-way flashers — serve important functions, it is the headlights that provide ongoing visibility. Remember, you should never look directly at very bright lights, including oncoming headlights, as this can temporarily impair your vision and be hazardous while driving.