In a CFA study seminar, the following comments were made: Comment 1: "In the short run, an increase in demand in a perfectly competitive industry will result in negative economic profit for some firms in the industry. " Comment 2: "In the long run, a permanent increase in demand in a perfectly competitive industry will result in zero economic profit for the firms in the industry. " Which of the following best describes the accuracy of these commentsComment 1 Comment 2（）①A. Correct Correct ②B. Correct Incorrect ③C. IncorrectCorrect
A. ①
B. ②
C. ③
参考答案：C
解析：
Comment 1 is incorrect because an increase in industry demand will increase equilibrium price and output. At the higher price, firms will earn positive economic profits in the short run because the higher price will exceed average total cost. Over the long run, however, new firms will enter the market to exploit the positive economic profits, causing prices to decline until all firms are again earning zero economic profit.