The donation game may be applied to markets. Suppose X grows oranges, Y grows apples. The marginal utility of an apple to the orange-grower X is "b", which is higher than the marginal utility ("c") of an orange, since X has a surplus of oranges and no apples. Similarly, for apple-grower Y, the marginal utility of an orange is "b" while the marginal utility of an apple is "c". If X and Y contract to exchange an apple and an orange, and each fulfills their end of the deal, then each receive a payoff of "b"-"c". If one "defects" and does not deliver as promised, the defector will receive a payoff of "b", while the cooperator will lose "c". If both defect, then neither one gains or loses anything.