Why is the profit-maximizing condition for a firm in perfect competition where marginal revenue equals marginal cost (MR = MC)?

• A. Marginal cost is the extra cost of producing one more unit; in perfect competition, price equals marginal revenue; profit is maximized where MR = MC.
• B. Because average revenue equals total cost.
• C. Because fixed costs are minimized.
• D. Because average total cost is minimized.

Answer: (A)