The service line
a) Carries air to the cab of the rig to cool it
b) Carries air to the parking brake to control the trailer brakes
c) Carries air to a relay valve that allows the trailer brakes to be applied quickly
Answer: c) Carries air to a relay valve that allows the trailer brakes to be applied quickly
If the answers is incorrect or not given, you can answer the above question in the comment box. If the answers is incorrect or not given, you can answer the above question in the comment box.