What is the purpose of a vehicle's seat belt?

The purpose of a vehicle's seat belt is primarily to secure occupants and prevent injury during sudden stops or collisions. Seat belts are designed to restrain the occupants of a vehicle, reducing the risk of injury by keeping them firmly in their seats. In the event of a sudden stop or an accident, a seat belt helps to distribute the forces of a collision across the stronger parts of the occupant's body, such as the chest and pelvis, thereby minimizing the risk of serious injury.

Using a seat belt is a critical safety measure, as unbelted occupants can become projectiles in a crash, greatly increasing their risk of injury or death. Seat belts also help keep occupants in their seats, ensuring that they remain in a position where airbags and other safety features can effectively protect them.

While other choices may touch on aspects of vehicle design and operation, they do not encompass the primary safety function a seat belt serves in protecting vehicle occupants.