What is the primary purpose of a seatbelt?

The primary purpose of a seatbelt is to keep passengers seated during a crash. In the event of a collision, a seatbelt restrains the occupants of the vehicle, preventing them from being ejected or thrown around inside the car. This is critical for reducing the risk of serious injury or death. Seatbelts are designed to work in conjunction with other safety features of a vehicle, such as airbags, to enhance overall protection. They help distribute the forces of a crash across the stronger parts of the body, minimizing damage and increasing the likelihood of survival.

The other options do not accurately reflect the essential function of a seatbelt. A seatbelt does not prevent the car from moving; it is not designed to assist with the driver's visibility; and while it may contribute to overall comfort by providing support, that is not its primary role. The main objective is safety during travel, making seatbelts a critical component of vehicular safety regulations.