What is the primary function of anti-lock brakes?

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

The primary function of anti-lock brakes (ABS) is to prevent wheel lock-up during braking. When a driver applies the brakes aggressively, particularly in slippery conditions, the wheels can lock up, leading to a loss of steering control and increasing stopping distances. ABS prevents this by modulating brake pressure to each wheel, allowing them to keep turning while braking. This system helps maintain traction between the tires and the road surface, enabling the driver to steer during a hard braking situation and reducing the risk of skidding. Options that suggest increasing vehicle speed, enhancing fuel efficiency, or providing additional engine power do not relate to the basic function of braking systems and are thus not valid in this context.