Answer:
The correct answer is option A.
Explanation:
A pure monopoly is a market where there is only single firm producing a good with no close substitutes. The firm is a price maker and faces a downward sloping demand curve.
The market demand curve and the demand curve of the firm are the same.
The firm is able to maximize profit at the point where the marginal revenue is equal to marginal cost. This output level is less than socially optimal level of ouput and creates a dead weight loss. A pure monopoly firm does not produces at allocative efficient level.