The opportunity cost of an item is what you give up to get that item.
I would think its the curves demand
Piaget would say that the group in which 7- to 10-year-old children are playing organized little league baseball and they have learned the formal rules of the game, and they play according to their shared knowledge is an example of heteronomous morality. In this stage children accept that all rules are made by some authority figure and their morality is imposed from the outside.
