Monopolistic competition is similar to a monopoly since both market structures have (b) downward-sloping demands for the firms. Firms in both markets face the downward-sloping demand curve for their products. In a monopoly, the firm demand is the same as the demand for the entire market (because they are the only seller). In monopolistic competition, however, the demand is only for that firm's product, which is a relatively small part of the overall market.