In order to maximize profit, a monopolistically competitive firm should produce the quantity where price equals marginal cost. price equals marginal revenue. marginal revenue equals marginal cost. marginal revenue equals average total cost

The objective of eact perfectly competitive firm is to choose the output levels in which the profit is maximized. This is obtained by calculating the optimal level at which the Marginal Cost = Market Price. And since a perfect competitive company cannot influence the price, therefore Market Price = Marginal Revenue. Hence the answer to this question is:

" marginal revenue equals marginal cost"