According to Article 51 of the Road Traffic Safety Law of the PRC and safety standards for passenger vehicles (GB 7258-2017), what is the mandatory pre-departure safety duty of a commercial passenger bus driver regarding seatbelts?

1. The driver must remind and ensure that all passengers have fastened their seatbelts before moving the vehicle and maintain reminders throughout the journey
2. The driver only needs to remind passengers sitting in the front row and seats next to emergency exits to wear seatbelts
3. The driver is only required to broadcast a seatbelt reminder when entering expressways or mountain roads
4. The driver does not need to verify seatbelts if the bus is equipped with passenger airbags