In the long run,a pure monopolist will maximize profits by producing that output at which marginal cost is equal to:

A) average total cost.
B) marginal revenue.
C) average variable cost.
D) average cost.

A pure monopolist maximizes profits at the level of output where marginal revenue equals marginal cost. This is because a monopolist has control over the price it charges, so it can sell additional units at a price lower than the current price, thereby increasing revenue. However, producing additional units also incurs additional costs, hence, the monopolist needs to balance the two at the point where marginal revenue equals marginal cost to maximize profits.