Final answer:
Children who are shorter than 150 cm or under 12 years old must sit in a booster seat while in a car to ensure proper seat belt fit and safety.
Step-by-step explanation:
Children who are seated in the rear seat and are either shorter than 150 centimeters (4 feet, 11 inches) or are 12 years old or younger must 2) sit in a booster seat. This requirement is part of safety laws that aim to protect children in case of a car accident. As children grow, their needs in terms of vehicle safety change, and using a booster seat ensures that the seat belt fits properly over their smaller bodies, offering better protection. This is similar to how seat belts are mandatory in other situations, like on a roller coaster or in an airplane, to ensure the safety of passengers.