A motor vehicle is abandoned in an alley of city A. A number of the residents of the area where the vehicle has been left complain to the city police to have the vehicle towed away. The police do nothing and the vehicle remains in the alley for months. A young man B is walking by the vehicle one day when the gas in the vehicle's gas tank explodes and sets B's clothes on fire which severely burns him. under what theory can the city be sued and what is the city's defense