Final answer:
The correct option is C) 3 psi per minute. combination vehicle air brake system should not lose air faster than 3 psi per minute, which ensures safety and operational efficiency.
Step-by-step explanation:
The rate at which a combination vehicle air brake system should not lose air is critical for maintaining safety and operational efficiency. The accepted standard for air pressure loss is less than 3 psi per minute for combination vehicles with the engine off and the brakes released. It should also be less than 4 psi per minute with the brakes applied. Therefore, the correct answer to the question is C) 3 psi per minute.
In a combination vehicle air brake system, the acceptable rate of air loss is typically measured in psi per minute. According to the options provided, the correct answer is A) 2 psi per minute. This means that the system should not lose more than 2 psi of air pressure in one minute.