What device on the trailer will not function if the electrical connection to the towing vehicle is missing or interrupted?

Your answer is correct because both the electronic braking system (EBS) and the lighting system on a trailer rely on the electrical connection to the towing vehicle. If this connection is missing or interrupted, the trailer's lights (such as brake lights, turn signals, and tail lights) will not work, which is crucial for safety and legal driving. Similarly, the EBS, which electronically controls the trailer's brakes to improve braking performance and stability, also depends on the electrical supply from the towing vehicle.

On the other hand, the traction control system (TCS) is part of the towing vehicle, not the trailer, so it is not affected by the trailer's electrical connection. Knowing this distinction helps you understand that any electrically powered system on the trailer requires a proper connection for functioning.