Answer :
Final answer:
The tractor protection valve prevents sudden air loss from the reservoirs in case of a ruptured main discharge line between the compressor and the reservoirs in a vehicle's brake system. Hence the correct answer is option A
Explanation:
The action that would prevent sudden air loss from the reservoirs if the main discharge line between the compressor and the reservoirs ruptured is the tractor protection valve. The tractor protection valve is a safety feature in the brake system of a vehicle that isolates the air supply to the trailer in case of a rupture or loss of pressure in the main line. This valve prevents the sudden loss of air pressure and ensures that the remaining air in the reservoirs can still be used for braking.
Hence the correct answer is option A
