Is a private touring coach (Reisebus) permitted to use a dedicated city bus lane displaying sign StVO § 53/25 without supplementary plates?

1. Yes, because all Category D vehicles are legally classified as buses
2. No, only scheduled public transport buses (Kraftfahrlinien) are permitted unless an additional sign explicitly allows coaches
3. Yes, provided the coach has at least 16 passengers on board
4. Yes, during off-peak traffic hours between 20:00 and 06:00