What is the primary purpose of seat belts?

The primary purpose of seat belts is to reduce injuries during a crash. Seat belts are designed to secure occupants in their seats, preventing them from being thrown forward or ejected out of the vehicle in the event of a collision or sudden stop. By restricting the movement of passengers and drivers, seat belts significantly decrease the likelihood of serious injury or death. They work by distributing the forces of a crash across stronger parts of the body, such as the pelvis and ribcage, rather than allowing those forces to concentrate on more vulnerable areas.

The other options do not accurately reflect the safety role of seat belts. While comfort may be a secondary factor in seat belt design, it is not their primary function. Seat belts do not play a role in vehicle theft; rather, that is typically addressed through mechanisms like locks and alarms. Additionally, seat belts do not influence the speed of the vehicle, as their purpose is entirely safety-focused rather than performance-related.