Who is legally authorized to drive on a marked bus lane (Busfahrstreifen, StVO § 53/25) that has no additional supplementary signs?

1. Only scheduled public service buses (Kraftfahrlinien) and emergency vehicles on duty
2. All buses, taxis, and private passenger cars carrying three or more occupants
3. Any heavy commercial vehicle with a gross weight exceeding 3.5 tonnes
4. Private touring coaches and rental vans without exception