What pressure does the safety valve reduce at?

Answer: C — 150 psi

The safety valve is a critical component in an air brake system, designed to protect against excessive pressure that could potentially damage the system. It is specifically set to release air when it reaches a pressure exceeding 150 psi. This setting is meant to prevent the pressure from rising to a level that could compromise the integrity and functionality of the air brake system. Thus, when the air pressure in the system rises to 150 psi, the safety valve activates to ensure that the pressure is maintained at safe levels, allowing for optimal operation of the air brakes and enhancing overall safety.