Under the technical standard Technical Specifications for Safety of Power-Driven Vehicles Operating on Roads (GB 7258-2017), what speed threshold activates the automatic passenger door safety interlock?

1. When vehicle speed exceeds 30 km/h only
2. When vehicle speed exceeds 60 km/h on expressways
3. There is no speed interlock required on city buses
4. When the vehicle speed exceeds 5 km/h, the passenger doors cannot be opened via normal electrical switches, and if doors are open, the vehicle must be prevented from accelerating normally