Which of the following brakes is explicitly used to keep a vehicle stabilized and stationary when parked?

Which of the following components is operated to apply and release parking brakes in heavy commercial vehicles equipped with air brakes?

_____ brakes are a type of brake in which the fluid from the master cylinder is forced into a caliper where it presses against a piston. The piston in turn squeezes two brake pads against the disc (rotor), which is attached to the wheel, forcing it to slow down or stop.