怎么理解垄断竞争但是有很多参与者？

问题如下：

QuestionWhich characteristic(s) hint(s) at the presence of a monopoly in the market?

选项：

A.

A sole firm holding a concentration ratio of 100%

B.

A Herfindahl-Hirschman index standing at zero

C.

Both a 100% concentration ratio and a Herfindahl-Hirschman index of zero

解释：

1. Correct, as a concentration ratio that equals 100% indicates that a single firm dominates the entire market, suggesting a monopoly.
2. Incorrect, since a Herfindahl-Hirschman index (HHI) at zero would not signify a monopoly. In fact, if a single entity holds a monopoly, the HHI would be at its maximum, not zero.
3. Incorrect, because while a concentration ratio of 100% does indicate a monopoly, a Herfindahl-Hirschman index of zero contradicts this. An HHI of zero suggests diverse market competition, whereas a monopoly would result in a maximum HHI value.

•

A正确，当集中度等于100%时，表明一家公司主导了整个市场，这表明存在垄断。
B不正确，因为赫芬达尔-赫希曼指数(HHI)为零并不意味着垄断。事实上，如果单一实体垄断，HHI将达到最大值，而不是零。
C不正确，因为虽然集中度达到100%确实表明存在垄断，但赫芬达尔-赫希曼指数为零则与此相矛盾。HHI为零表明市场竞争多样化，而垄断将导致HHI值最大化。