What type of brake system applies and releases the brakes when using the brake pedal?

Answer: A — Service brake system.

The service brake system is designed to apply and release the brakes in response to the driver's input through the brake pedal. In a commercial vehicle, this system allows the driver to slow down or stop the vehicle as needed during normal driving conditions. It typically operates on air pressure in vehicles equipped with air brakes, meaning that when the driver presses the brake pedal, air is directed to the brake chambers, engaging the brakes to provide necessary stopping power. The functionality of the service brakes distinguishes them from other systems. For instance, the emergency brake system is intended as a backup in case the primary braking system fails, and it is activated differently. The parking brake system is mainly used to keep the vehicle stationary when parked and is typically applied when the vehicle is not in operation, rather than during regular driving. This emphasis on the role of the service brake system clarifies its importance in safe vehicle operation and everyday driving scenarios.