A single-unit applied leak check drops from 120 psi to 115 psi over two minutes with the engine off and full brake application held. How should this result be interpreted?

1. It passes because the loss averages 2.5 psi per minute, below the 3 psi per minute limit
2. It fails because any pressure drop is illegal
3. It fails because single units are allowed only 1 psi total loss
4. It cannot be evaluated because gauges are never used in leak checks