What is the purpose of the air compressor in an air brake system?

Answer: B — To pressurize the air needed for braking

The purpose of the air compressor in an air brake system is to pressurize the air needed for braking. This is crucial because air brakes function by using compressed air to create force that applies the brakes. When you press the brake pedal, a series of valves and chambers utilize the pressurized air to activate the brake shoes against the drum, generating the necessary friction to slow down and stop the vehicle. Understanding the function of the air compressor is key to recognizing how the entire air brake system operates. Without adequate air pressure provided by the compressor, the braking system would be unable to function effectively, presenting a safety hazard. The other choices do not accurately reflect the role of the air compressor; it does not cool brake components, control the vehicle’s speed, or provide power to the electrical system. Each of these functions is served by other components in the vehicle's system.