When regulating a natural monopoly, government officials face a dilemma in that

a.       marginal cost pricing will result in a price higher than consumers are willing and able to pay.

b.       pricing at technological efficiency will force the firm to take economic losses.

c.       long run average total costs are constantly increasing.

d.       a subsidy to the monopoly is needed to make the firm profitable.

e.       none of the above are true.

然后这道题应该选哪个？谢谢了