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

Answer: B — To supply air pressure

The primary purpose of the air compressor in an air brake system is to supply air pressure. In air brake systems, the compressor generates compressed air, which is crucial for the operation of air brakes. This compressed air is stored in the air tanks and is used to activate the brake mechanism when the driver applies the brake pedal. The ability of the air compressor to maintain the right amount of air pressure directly impacts the responsiveness and effectiveness of the braking system. The other functions mentioned, such as monitoring vehicle speed or cooling down brake components, do not align with the role of the air compressor. Instead, these functions are managed by different systems or components in the vehicle.