Which Is the Most Valid Criticism of the Regulation of Natural

Which is the most valid criticism of the regulation of natural monopolies and other firms subject to regulation by regulatory commissions?

A) It is difficult to find enough honest people to serve on regulatory commissions.
B) Such regulation is unnecessary and amounts to creeping socialism.
C) Many members of such commissions are appointed rather than being elected.
D) Regulated firms may have little incentive to contain costs since they are assured a "fair" return above costs.