The correct answer is D. All of the above.
In a monopolized market, the monopolist is the only seller of a good or service. This means that the monopolist has a great deal of market power and can set the price of its product. The monopolist will set the price at a level where marginal revenue equals marginal cost. This is the point where the monopolist makes the most profit.
In the long run, the monopolist will produce at a level where long-run marginal cost equals long-run average cost. This is the point where the monopolist minimizes its costs.
Therefore, in the long run, a monopolized market is in equilibrium when the monopolist produces where the price is equal to long-run marginal cost and long-run average cost, and the price is not below the long-run average cost.
Here is a more detailed explanation of each option:
- Option A: Zero economic profit is earned by the monopolist.
In the long run, a monopolist will only earn a normal profit. This is a profit that is just enough to cover the costs of production, including the opportunity cost of capital. The monopolist will not earn an economic profit, which is a profit that is greater than the opportunity cost of capital.
- Option B: Production takes place where the price is equal to long-run marginal cost and long-run average cost.
In the long run, the monopolist will produce where the price is equal to long-run marginal cost and long-run average cost. This is the point where the monopolist makes the most profit.
- Option C: Production takes place where long-run marginal cost is equal to marginal revenue, and the price is not below the long-run average cost.
In the long run, the monopolist will produce where long-run marginal cost is equal to marginal revenue. This is the point where the monopolist minimizes its costs. The price will not be below the long-run average cost, because the monopolist would not be able to cover its costs if the price were below the long-run average cost.