What must all connections to fuel supply cylinders external to the driver compartment be?

Answer: B — Sealed and vented from those compartments

Connections to fuel supply cylinders external to the driver compartment must be sealed and vented from those compartments. This requirement is crucial for safety to ensure that any gas that may escape can do so in a controlled manner without accumulating inside the driver compartment, which could create dangerous conditions. Sealing these connections prevents gas leaks into the vehicle, while venting allows for any potential buildup to dissipate safely outside. Having sealed and vented connections also means that if there were a failure or leak, harmful gas would not pose a risk to the occupants. Proper installation and maintenance of these connections are essential for safe operation and compliance with regulatory standards. Ensuring that fuel supply systems are designed with adequate ventilation contributes significantly to the overall safety of CNG-powered vehicles on the road.