According to the Road Traffic Safety Law, what is the driver's responsibility regarding passenger safety and the use of seat belts on highway passenger coaches?

1. The driver only needs to worry about their own seat belt and may ignore passengers
2. The driver must remind and ensure that all passengers have their seat belts fastened before driving, and periodically check compliance throughout the journey
3. Seat belts are only required if the vehicle is traveling over 100 km/h
4. Passengers under 18 years of age are prohibited from wearing seat belts