问题
单项选择题
Consider two markets; one has a Herfindahl-Hirschman Index (HHI) of 50, while the other has a four-firm concentration ratio equal to 2%. Which of the following statements most accurately describes these two markets（）
A. Both of these markets are monopolies.
B. The market with the HHI equal to 50 is very competitive, while the other market has low competition.
C. Both markets are highly competitive.
答案
参考答案：C
解析：
An HHI concentration measure of 50 is very low, indicating a high degree of competition. A four firm concentration ratio of 2% indicates a high level of competition. For both the four-firm ratio and the HHI, the higher (lower) the concentration measure, the lower (greater) the degree of competition.