What is true about parking brakes?

The statement that parking brakes operate separately from service brakes is accurate. Parking brakes, often referred to as handbrakes or emergency brakes, are designed to hold the vehicle stationary when parked, preventing it from rolling. They function independently of the vehicle's primary braking system, or service brakes, which are used for stopping the vehicle while driving.

This separation is crucial because it ensures that the car remains secure when parked, regardless of the service brake system's condition. In the event of a failure of the service brakes, the parking brake can still provide a level of safety by keeping the vehicle in place. This highlights the importance of having a backup braking system that operates independently.

The other options present misconceptions about how parking brakes function. For example, parking brakes do not necessarily act on 'drive' wheels or all four brakes in the case of four-wheel drive vehicles. The design can vary based on the vehicle's make and model, and in some vehicles, parking brakes may only engage one set of wheels, not specifically the left side.