(a) (7.5 marks) Fully explain the economic differences between a bargain and a promise. In your explanation explain how the economic steps that occur effect the indifference curves of the promisee and promisor when a promise is made and a bargain is reached. (b) (7.5 marks) If in anticipation of a promise, a person gives something up, what are the economic arguments in favour or against treating this as a bargain