What is the primary function of a seatbelt?

The primary function of a seatbelt is to hold passengers in place during an accident. This safety device is designed to restrain the occupants of a vehicle, significantly reducing the risk of injury during collisions. In the event of a crash, the force of the impact can cause unrestrained passengers to be thrown forward or ejected from the vehicle, leading to serious injuries or fatalities. Seatbelts work by distributing the forces of a crash over the stronger parts of the body and keeping the occupant secured in their seat, helping to prevent ejection from the vehicle and minimizing movement that can lead to secondary impacts inside the car.

The other choices do not accurately reflect the primary purpose of a seatbelt. While comfort can be a secondary consideration in the design of seatbelts, it is not their main function. Seatbelts do not have any role in controlling vehicle speed or signaling other vehicles, which are entirely different aspects of driving safety and care.