问题
单项选择题
Which of the following is least likely to be considered a reason for the existence of a natural monopoly（）
A. Firms that can maximize profit when price equals marginal cost.
B. Firms that have significant economies of scale.
C. Firms that have significant economies of scope.
答案
参考答案：A
解析：
Profit maximization occurs when price equals marginal cost in a perfectly competitive industry, not a monopoly. A natural monopoly exists when economies of scale or scope are so significant that total industry production should be produced by only one firm. In this case, average total cost declines over the entire range of demand.