问题
单项选择题
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.
答案
参考答案：C
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.