Why might product development be efficient and why might it be inefficient? Product development is efficient if the marginal social benefit from an improved product _______. Product development is inefficient because in monopolistic competition, _______. A. is greater than or equal to its marginal social cost; firms receive a greater return from advertising than from product development B. equals its marginal social cost; product development raises the price the firm can charge, which decreases the quantity sold C. equals its marginal social cost; profit is maximized when marginal revenue equals marginal cost, and marginal revenue is less than price D. increases the price that a firm can charge; profit is maximized when marginal revenue equals marginal cost, and marginal revenue is less than price