Final answer:
The brake pedal in an air brake system controls the air pressure used to apply the brakes. Air brake systems differ from hydraulic systems as they must manage air compression to maintain efficiency. So, the correct option is C) controls the air pressure applied to put on the brakes
Step-by-step explanation:
The brake pedal in an air brake system controls the air pressure applied to put on the brakes. This is because when you press the brake pedal, the pressure is transmitted through the air brake system to apply the brakes at the wheels. In a hydraulic brake system, which uses Pascal's principle, the force exerted on the brake pedal is increased by a lever and hydraulic system to apply braking force at the wheels.
However, this is different from an air brake system where air pressure is utilized and must be managed carefully to prevent air from being compressed in the lines, which could lead to inefficiencies or a delayed braking response.
So, the correct option is C) controls the air pressure applied to put on the brakes