Suppose you have your own pizza delivery business and receive a call to deliver to A remote client. You need to decide whether to take the call. If you don't, there are no consequences, since someone else will. Based on the distance to the client, you calculate that it would cost you $5 to deliver, and expect to receive $6 for the service. You also pay monthly rent for the car, which on average, based on past experience, comes down to about $2 per trip. Your time doesn't matter, as you have nothing more enjoyable or useful to do for the time being. How do you make your decision? What economic principle is at work in your decision process?