单选题 Which of the following most accurately describes the competitive structure that is characterized by a firm that operates with the lowest average total cost and has the capacity to produce all of an industry's output?

A、

A. Oligopoly.
B、

B. Competitive monopoly.
C、

C. Natural monopoly.

【正确答案】 C

【答案解析】A natural monopoly is characterized by a single firm within the industry that has sufficient capacity to meet the entire demand of an industry because at that scale the lowest average total cost is achieved.