单选题 A profit maximizing firm will expand output as long as marginal revenue is:

A、 less than marginal cost.
B、 greater than marginal cost.
C、 less than average variable cost.

【正确答案】 B

【答案解析】A purely competitive firm will tend to expand its output so long as the market price (marginal revenue) is greater than marginal cost. In the short term and long term, profit is maximized when P = MC.