When the Perfectly Competitive Firm Produces the Quantity of Output

When the perfectly competitive firm produces the quantity of output at which marginal revenue equals marginal cost, it naturally

A) produces the quantity of output at which marginal cost equals price, since for the perfectly competitive firm price equals marginal revenue.
B) produces the quantity of output at which short-run average total cost equals price, since for the perfectly competitive firm short-run average total cost equals marginal revenue.
C) earns a profit, since equating marginal revenue and marginal cost guarantees profit.
D) takes a loss.