If the firm' s average cost curves are U-shaped, why does its average variable cost curve achieve its minimum at a lower level of output than the average total cost curve?
A.需求曲线d相切于平均可变成本曲线AVC的最低点
B.均收益AR小于平均可变成本AVC
C.边际收益MR等于短期边际成本SMC的利润最大化均衡点
D.以上都对