单选题 A monopolist will continue expanding output as long as: A. marginal revenue is positive. B. marginal revenue is greater than marginal cost. C. average total costs are declining.

【正确答案】 B

【答案解析】The optimum behavior of all firms is to produce until the point where MR = MC. So, the monopolist can increase total profit by increasing production as long as marginal revenue is greater than marginal costs.