Final answer:
The anti-lock braking system in buses prevents the brakes from locking up, improving safety by maintaining traction and steering control during emergency braking.
Step-by-step explanation:
The true statement for an anti-lock braking system (ABS) in buses is that it prevents the brakes from locking up. ABS is designed to help maintain control of the vehicle during emergency braking situations by preventing the wheels from locking, which would otherwise lead to skidding. The ABS does this by modulating brake pressure to each wheel, allowing them to maintain traction with the road surface. This safety feature is crucial in maintaining steering ability during a hard stop and can indeed shorten the stop distance under certain conditions. However, ABS does not increase the braking distance, reduce fuel efficiency, or eliminate the need for regular brake maintenance.