What must be done before refueling a CNG vehicle?

Answer: B — Ensure the vehicle is parked safely and the engine is turned off

Before refueling a CNG vehicle, it is essential to ensure that the vehicle is parked safely and that the engine is turned off. This practice is crucial for safety reasons; having the engine off minimizes the risk of fire or explosion during the refueling process, as combustion engines can pose a hazard when near flammable gases like compressed natural gas (CNG). Additionally, parking the vehicle safely ensures that it is stable and reduces the risk of accidental movement during refueling. The other options, while they may relate to vehicle safety or maintenance, do not directly address the immediate requirements for safely handling the refueling procedure. For instance, turning off hazard lights is not relevant to the refueling process itself; rather, it pertains to signaling to other drivers. Increasing tire pressure, while important for vehicle maintenance, does not impact the safety of refueling. Opening the windows does not directly influence the refueling process and is not a standard practice related to CNG refueling safety.