If a dual air system has one system low on pressure, what is a likely braking outcome?

Answer: B — Either the front or rear brakes will not be operating fully

Dual air brake systems split braking into two independent circuits to provide a backup. If one circuit runs low on pressure, the brakes fed by that circuit can’t apply with full force, while the other circuit still works normally. That means you won’t have braking on all wheels with the same strength—the brakes on the low-pressure side won’t be operating fully, while the other circuit remains able to apply as usual.