单选题 Firms in a perfectly competitive industry will increase their output until which of the following conditions is met? A. Total revenue equals price. B. Marginal cost equals price. C. Marginal revenue equals average fixed cost.

【正确答案】 B

【答案解析】When a firm operates under conditions of perfect competition, marginal revenue always equals price. Under perfect competition, price is constant (a horizontal line) so marginal revenue is constant. Therefore a firm will increase output until marginal cost equals price.