What function does a parking brake serve?

Answer: B — It is used to secure a vehicle when parked.

The primary function of a parking brake is to secure a vehicle when it is parked. This brake system is designed to hold the vehicle stationary, preventing it from rolling away, especially on inclines or uneven surfaces. When engaged, the parking brake keeps the vehicle in place, ensuring that it remains safely parked until the driver is ready to drive again. While other options may sound relevant, they do not accurately reflect the main purpose of the parking brake. For instance, stopping the vehicle in an emergency is typically the role of the regular foot brake. Additionally, the parking brake doesn't actively reduce tire wear during normal driving; its function is specifically for securing a parked vehicle rather than influencing tire condition. Lastly, while some vehicles may have features that engage the parking brake automatically, this is not a universal characteristic or a defining function of the brake itself.