A filling station (gas station) is to be set up for fully automated operation. Drivers swipe their credit card through a reader connected to the pump; the card is verified by communication with a credit company computer, and a fuel limit is established. The driver may then take the fuel required. When fuel delivery is complete and the pump hose is returned to its holster, the drivers credit card account is debited with the cost of the fuel taken. The credit card is returned after debiting. If the card is invalid, the pump returns it before fuel is dispensed.

Your task is to determine what design pattern(s) is/are to be applied in the system(Decorator, Factory Method, Strategy, Singleton, Adapter, Facade, Template Method, Iterator, Observer, Command, Builder, Chain of Responsibility, Memento, Visitor, State, Flyweight, Mediator, Prototype, Proxy.). Explain your choice(s) clearly.