What is the function of the Anti-lock Brake System (ABS) in air brake systems?

Answer: B — To prevent wheel lock-up during hard braking

The function of the Anti-lock Brake System (ABS) in air brake systems is primarily to prevent wheel lock-up during hard braking. This is crucial for maintaining steering control and stability of the vehicle, especially in emergency braking situations or on slick surfaces. When the brakes are applied forcefully, the ABS modulates brake pressure to each wheel, ensuring that the wheels do not completely stop rotating. This allows the driver to maintain better control during braking, significantly reducing the risk of skidding and enhancing overall safety. In the context of braking systems, while the other options describe various aspects of braking, they do not accurately represent the core purpose of ABS. The system is specifically engineered to counteract wheel lock-up, and therefore it is instrumental in enhancing vehicle safety and responsiveness.