问题
单项选择题
Which of the following is a characteristic of perfect competition（）
A. There are a few sellers.
B. The products of different firms are sold at different prices.
C. There are no barriers to entry into the market.
答案
参考答案：C
解析：
The only true statement listed in the question is that, under perfect competition there are no barriers to entry into the market. Each of the other possible answers is not a characteristic of perfect competition. While the competitors can earn positive economic profits in the short-run, they cannot earn long term economic profits due to ease of entry and exit.