How many fire extinguishers must be present in a trolleybus, and where must they be secured if places for their mounting are not provided for by the design?

1. 1One fire extinguisher, which must be secured in the driver’s cab.
2. 2Two fire extinguishers, which must be secured in the driver’s cab.
3. 3Two fire extinguishers, one of which must be secured in the driver’s cab and the other in the passenger compartment.
4. 4Three fire extinguishers, one of which must be secured in the driver’s cab, the second in the passenger compartment, and the third in the luggage compartment.