Final answer:
California law mandates children to be secured in the rear seat of a vehicle with proper restraints until they are 8 years old or reach a height of 4 feet 9 inches.
Step-by-step explanation:
Under California law, all children must be secured in the rear seat of a vehicle in an approved child safety seat or booster seat until the age of 8 years old, or until they reach a height of 4 feet 9 inches. This requirement is part of California's effort to enhance the safety of children when they are passengers in a vehicle. Keeping younger children in the rear seat with proper restraints significantly reduces the risk of injury or death in a vehicular accident.