What must be checked regularly to ensure air brakes function correctly?

Answer: B — The condition of the air lines and fittings

Regularly checking the condition of the air lines and fittings is crucial for the proper functioning of air brakes. Air brakes operate by using compressed air to engage the brake system, and any leaks or damage in the air lines can severely affect performance. If the air lines are not in good condition, it can lead to insufficient air pressure, resulting in delayed or incomplete braking. Ensuring that all connections are secure and that there are no signs of wear, cracks, or leaks is essential for maintaining the overall safety and efficiency of a vehicle’s braking system. This proactive maintenance helps prevent brake failures, which can pose serious risks while driving.