Under Cameroonian law, what is the mandatory rule regarding safety seatbelts for occupants of passenger cars?

1. Seatbelts must be fastened by the driver and all front and rear seat passengers equipped with belts
2. Only the driver is legally required to wear a seatbelt
3. Seatbelts are mandatory only on expressways outside cities
4. Seatbelts are optional for passengers over 60 years of age