Which condition indicates a vehicle should be rejected based on the airbrake system's performance?

The correct answer identifies a critical performance threshold for the airbrake system on a vehicle, specifically regarding the acceptable limit of air pressure leakage when the brakes are applied. When the leakage exceeds three psi during a test, it signifies that the airbrake system may not hold pressure effectively, which can lead to a failure in maintaining appropriate braking performance. A leak in the system compromises the effectiveness and safety of the brakes, therefore ensuring that the vehicle meets the required standards for safe operation.

In contrast, having a governor cut-out pressure of less than ninety psi may raise concerns, but it doesn't directly indicate a failure concerning air pressure retention when the brakes are applied. The low pressure warning system is a safety feature that should function appropriately, but if it fails to activate at pressures above seventy psi, it may indicate a malfunction without directly impacting braking effectiveness. Lastly, while a time to build pressure exceeding three minutes might suggest inefficiencies in the air system, it isn't as directly indicative of a performance failure related to braking effectiveness like the leakage issue is. Hence, the leakage criteria stand out as a clear reason to reject a vehicle based on airbrake performance.