单选题 Firms in perfectly competitive markets and firms operating in a market characterized by monopolistic competition have several things in common. Which of the following is least likely one of them?

A. Both maximize economic profit.
B. Both face perfectly elastic demand curves.
C. Both operate in markets that have low or no barriers to entry.

【正确答案】 B

【答案解析】The only item listed in the question that monopolistic competition and pure competition do not have in common is a perfectly elastic demand curve. Under pure competition, producers face a perfectly elastic demand curve, whereas price searchers face downward sloping demand curves.