If an industry has a four-firm concentration ratio equal to one hundred percent, then it is definitely the case that the industry is
A) a monopoly.
B) perfectly competitive.
C) monopolistically competitive.
D) either a monopoly or an oligopoly.

Question

Quizplus · Accepted Answer

A four-firm concentration ratio of 100% indicates that the top four firms control the entire market, which means the industry is either a monopoly (one firm) or an oligopoly (a few firms).

If an Industry Has a Four-Firm Concentration Ratio Equal to One