Children aged 4-8 years and under 4 feet, 9 inches tall must use which type of safety device?

For children aged 4 to 8 years who are under 4 feet, 9 inches tall, using a belt positioning booster seat is the correct safety device. Booster seats are essential for this age group because they help position the vehicle's seat belt properly across the child's body. When a seat belt is not positioned correctly, it may not provide adequate protection in the event of a crash, increasing the risk of injury.

Children in this age range are typically not large enough for the vehicle's seat belts to fit them safely without additional support, which is where the booster seat plays a critical role. It elevates the child so that the seat belt fits over their shoulder and across their lap properly, ensuring their safety while traveling in a vehicle.

Other options, such as using just a seatbelt or no restraints, do not provide the necessary support and protection for children of this age and size. Additionally, using only a traditional seatbelt could lead to poor fit and increase the likelihood of injury during an accident. Therefore, choosing the booster seat is the best practice for ensuring safety in the vehicle.