What information must be included on a customer warning sign at an LP-gas dispenser?

The requirement to include specific information on a customer warning sign at an LP-gas dispenser is fundamentally about safety and risk mitigation. Including the instruction to extinguish all pilot lights and turn off the engine is essential because it directly addresses potential ignition sources that could lead to a fire or explosion when dealing with liquefied petroleum gas. LP-gas is flammable, and any open flame or spark can lead to dangerous situations.

Therefore, this information serves as a critical reminder to customers to take these measures before starting any fueling process, significantly reducing the risk of accidents associated with LP-gas. This focus on safety is why this information is mandated on warning signs, ensuring that users are well aware of the precautions necessary when interacting with LP-gas systems.

The other options might be valuable in certain contexts, but they do not specifically emphasize the immediate hazards presented during the dispensing process or the most critical actions that must be taken to prevent incidents.