Final answer:
Under the GDL rule, all passengers in the car must wear seat belts.
Step-by-step explanation:
The GDL (Graduated Driver Licensing) rule requires all passengers in the car to wear seat belts. This rule is implemented to protect individuals from injuries in case of accidents and to reduce the burden on society for providing medical and physical care for injured drivers. Seat belts are considered a safety measure that helps prevent serious injuries and saves lives.