What is the purpose of a seat belt?

The purpose of a seat belt is to secure occupants and prevent injuries during a crash. Seat belts are designed to restrain the body's movement in the event of a collision, helping to reduce the risk of being thrown against the interior of the vehicle or ejected from it. By keeping the occupants securely positioned, seat belts significantly enhance safety and reduce the severity of injuries for those involved in car accidents.

The other options don't capture the primary safety goal of seat belts. While comfort and seating posture may be secondary considerations, the fundamental function of a seat belt is to protect passengers. Moreover, seat belts do not provide freedom of movement; rather, they are meant to limit excessive movement to ensure safety during travel.