The monopolistically competitive seller maximizes profit by producing at the point where:

A) total revenue is at a maximum.
B) average costs are at a minimum.
C) marginal revenue equals marginal cost.
D) price equals marginal revenue.

The monopolistically competitive seller maximizes profit by producing at the point where marginal revenue equals marginal cost. This is because at this point, the seller is producing the quantity of output where the last unit produced generates the same amount of revenue as the cost to produce it. Any quantity produced beyond this point would result in a decrease in profits as the cost to produce each additional unit exceeds the revenue earned from selling it. Therefore, the option where marginal revenue equals marginal cost is the best choice.