11. When there are positive externalities in consumption, what can be concluded about the output of the market? A. Output must be above the allocation efficient level. B. Output must be at the allocationficient level. C. Output must be below the allocation efficient level. D. Output can be above or below the allocation efficient level. In the short run, a firm produces an extra unit of output. Which of the firm's production costs will change? | A. fixed cost only B. fixed cost and variable cost C. variable cost only D. variable cost and total cost 4. The table shows a firm's total and marginal costs. What is the average fixed cost of producing 6 units? output total cost ($) marginal cost ($) 1 340 40 375 35 W N 400 25 435 35 475 40 A $50 B $60 C $180 D $300