What is the minimum number of operative fire extinguishers which must be carried on a bus (single deck)?

You are correct. For single-deck buses, at least one functional fire extinguisher must be carried on board. This rule ensures that in the event of a fire, immediate action can be taken to protect passengers' safety. Additional requirements for more extinguishers may apply at higher capacities or with different bus types, but the minimum for a standard single-deck bus is one fire extinguisher. This is set by German vehicle safety regulations to ensure basic emergency preparedness. Knowing this helps you select the right option in similar questions about equipment requirements for different vehicle types.