The correct answer is C. earn maximum profits.
A monopolist is the only seller of a good or service in a market. This means that they have a great deal of power over the price they charge and the quantity they produce. A monopolist’s goal is to maximize profits, which means they will try to produce the quantity of output where marginal revenue equals marginal cost. This is the point where the monopolist will earn the highest possible profit.
Option A is incorrect because a monopolist does not necessarily want to charge a very high price. In fact, if they charge a price that is too high, they may not be able to sell all of their output. Option B is incorrect because a monopolist does not necessarily want to sell all of what they have produced. In fact, if they produce too much output, they may not be able to charge a high enough price to earn maximum profits. Option D is incorrect because a monopolist does not necessarily want to ensure that costs are a declining function of output. In fact, if costs are declining, the monopolist may not be able to earn maximum profits.