Answer :
Final answer:
A tractor protection valve is an important safety device in an air brake system of a tractor-trailer.
Explanation:
The correct answer is c. when it closes it allows air to leak from the tractor lines.
A tractor protection valve is an important safety device in an air brake system of a tractor-trailer. It is designed to keep the air in the tractor in the event the trailer air leaks. It is controlled by the trailer air supply valve in the cab, meaning it allows for the control of air flow between the tractor's brake system and the trailer's brake system.
However, it does not allow air to leak from the tractor lines when it closes. In fact, when it closes, it blocks the flow of air between the tractor and the trailer, providing a vital safeguard for the tractor's brake system.
