Answer:
D) control the desired price and output to maximize profits, but a perfectly competitive firm can only choose the desired output.
Step-by-step explanation:
Firms competing in perfectly competitive markets are price takers, meaning that they cannot set the price of their products or services, but monopolists can actually set the price of their products or services because their market power is high enough to do so. Also, a monopolist can choose to lower or increase its output depending on the resulting profits.
This excessive market power is the reason why natural monopolies are usually regulated by the governments and many monopolistic firms are forced to split into smaller firms that compete against each other.