I am assuming you are talking about the graph.
The monopoly will probably choose the Price 1 x Quantity 1 = that means, Point B
A monopoly is a situation of legal privilege or market failure, in which there is a producer or economic agent (monopolist) that has a great market power and is the only one in a given industry that has a product, good, resource or service determined and differentiated. The monopolist controls the quantity of production and the price, although not simultaneously, since the choice of production or price determines the position one has regarding the other; that is to say, the monopoly could first determine the production rate that maximizes its profits and then determine, by using the demand curve, the maximum price that can be charged to sell said production.
C is the correct answer.
The correct answer is C.
A monopoly is a market structure where a single firm serves the whole demand of a specific good or service. It does not face competitors, therefore, such firm has absolute market power to decide the price charged for its products.
So, the monopoly is able to charge a higher price than in a perfect competition scenario where the price would be set at the intersection betweeen the demand function and the marginal cost function.
Instead, the quantity sold in the monopoly (q*) is determined by the intersection of the marginal revenue and marginal cost curves, and the monopoly price is computed by substituting q* in the expression of the demand function (because the demand function relates price and quantity).
The result is 15$ as the picture shows.