All four options given can be reasons for the existence of headlights, signal lights, and taillights. However, the most accurate and general answer would be to "communicate with other drivers." The purpose of these lights is to signal your intentions on the road and to communicate with other drivers about your movements. They ensure safety and help in avoiding accidents by indicating when you are turning, changing lanes, stopping, or reversing. While they also play a role in customizing a vehicle's appearance or avoiding tickets, their primary purpose is to allow effective communication between drivers on the road.
