What is the primary purpose of using seat belts?

The primary purpose of using seat belts is to prevent ejection and keep passengers safe during a vehicle collision or sudden stop. Seat belts are designed to securely hold occupants in their seats, minimizing the risk of being thrown from the vehicle, which can result in serious injury or death. They work by distributing the force of an impact across the stronger parts of the body and keeping occupants properly positioned within the vehicle. This means that in the event of a crash, a seat belt significantly reduces the likelihood of injury by preventing individuals from being ejected or colliding violently with the interior of the car.

In contrast, enhancing vehicle performance pertains to aspects like engine efficiency and aerodynamics, which do not relate to safety features like seat belts. Adjusting seating position is a separate function of vehicle ergonomics, and while compliant seat belt use is crucial, it is not related to the laws that govern vehicle registration. Therefore, the sole focus of seat belts is on the safety of passengers within a moving vehicle, making the second option the most pertinent answer.