During a Minnesota CDL air-brake check, pressure is built to cut-out, the engine is off, brakes are released, and a straight truck loses 4 psi in one minute. What does that mean?

1. It fails because a single vehicle should not lose more than 2 psi per minute released
2. It passes because any loss under 10 psi is acceptable
3. It passes only because the engine is off
4. It proves the spring brakes are adjusted