Which of the Following Correctly Describes a Natural Monopoly

Multiple Choice

Which of the following correctly describes a natural monopoly?

A) A natural monopoly is an industry in which products are differentiated from one another.
B) A natural monopoly exists if one large firm's long-run average cost curve is upward-sloping.
C) A natural monopoly is defined as a firm that operates in an industry that has significant regulatory barriers to entry.
D) A natural monopoly is an industry that exhibits economies of scale.