Fill in the blanks to make the following statements correct.
a. The term natural monopoly refers to an industry in which only a single firm can operate at its
b. A regulated natural monopoly that is forced to set its price equal to marginal cost will earn ______ if its long-run average costs are falling.
c. A regulated natural monopoly that is subject to average-cost pricing and operating on the downward-sloping portion of its LRAC curve will earn ______ profits. Since price ______ marginal cost, this outcome will not be allocatively efficient.
d. Marginal-cost pricing for a natural monopoly is an efficient pricing system, but it leads to ______ for the firm if average costs are falling.