Final answer:
The correct statement about anti-locking brake systems is that they prevent wheel lock-up during braking, ensuring better directional control. Other options, such as affecting fuel efficiency or functioning only in dry conditions, are not true.
Step-by-step explanation:
The statement about anti-locking brake systems (ABS) that is true is Option 2: It prevents wheel lock-up during braking. The ABS is designed to help maintain directional control during emergency stops by preventing the wheels from locking up. This can help the driver avoid skidding while braking.
The claim that ABS increases the stopping distance is not generally true. ABS can sometimes lead to a longer stopping distance on loose surfaces like gravel or snow, but on dry and wet roads, it is effective in maintaining control while stopping. The ABS is not only effective in dry conditions; rather, it is particularly valuable in wet and slippery conditions where wheel lock-up is more likely to occur. Additionally, ABS is unrelated to fuel efficiency; it does not reduce the fuel efficiency of a vehicle. The system operates only when needed, thus it has no continuous effect on fuel consumption.