NO.PZ2023010401000037
问题如下：
In an industry comprised of three companies, which are small-scale manufacturers of an easily replicable product unprotected by brand recognition or patents, the most representative model of company behavior is:选项：
A.oligopoly. B.perfect competition. C.monopolistic competition.解释：
The credible threat of entry holds down prices and multiple incumbents are offering undifferentiated products.
中文解析：
进入威胁压低了价格，多家老牌企业都在提供没有区别的产品。
根据题设，一个行业就3家公司，竞争者数量不多、产品无实质差异，也没有专利啥的保护，这个不就是石油市场嘛，为什么不选A呢
