Why does the Marginal Revenue line decline downward within the monopoly graph as it sells more of its products or services? Multiple Choice This is incorrect, the marginal revenue is stable in the monopoly market model. The profit maximization formula prevents a declining Marginal Revenue. Because the monopoly must lower prices to capture all the middle-income and lower-income customers along the demand curve who can only afford to pay moderate prices. The marginal revenue is always increasing with a monopoly