单选题 Under perfect competition, a firm will experience zero long term economic profit when: A. price is less than average total cost. B. MR is greater than ATC. C. MC = ATC = MR = price.

【正确答案】 C

【答案解析】Under perfect competition, a firm will experience zero long term profits when P = MC = MR = ATC. It recovers all costs including opportunity costs and earns zero economic profit.