sarah is the owner of the sales business. David runs outside to assist but trips over a container of gas that Michael, a salesman, has left outside when he fills up a new car that had arrived that day. The trip and fall is relatively minor, but the gas can spills, pooling gasoline around David. When David gets up, his steel-toed boots, whose leather was damaged, exposing the metal, scrapes the asphalt, creating sparks, which ignite the gasoline and cause the gas container to explode. David is badly burned and spends significant time home from work as he recovers.

explain why david can sue sarah under occupiers liability in tort