【判断题】If the marginal cost of producing the fifth unit of output is higher than the marginal cost of producing the fourth unit of output, then at five units of output, average total cost must be rising.
【单选题】In the short run, the marginal cost of the first unit of output is $20, the marginal cost of producing the second unit of output is $16, and the marginal cost of producing the third unit of output is ...