21. At output level 0C, total profits equal a. FHSR. b. OSZC. c. GZSR. d. ORGC.22. At output level 0C, average fixed cost is equal to a. ZV. b. GZ. c. ED. d. VC.23. For a competitive firm the demand curve a. is horizontal b. coincides with the marginal revenue curve. c. coincides with the average revenue curve. d. all of the above.24. In the short run, if price falls, the firm will respond by a. shutting down. b. equating average variable cost to marginal revenue. c. reducing output along its marginal cost curve as long as marginal revenue exceeds average variable cost. d. none of the above.25. In the short run, a competitive firmâs supply curve is a. its average variable cost curve to the right of the marginal cost curve. b. its marginal cost curve above the average variable cost curve. c. its marginal cost curves above its average cost curve. d. the horizontal summation of the marginal cost curves.26. In a constant cost competitive industry if price rises above its long-run equilibrium level, which of the following will not occur as the industry adjusts to a new LR equilibrium? a. New firms will enter the industry. b. Economic profit will be eliminated. c. Input prices will rise. d. Existing firms will increase production.27. The term increasing cost industry is used to describe a. a firm with a rising average cost curve. b. an industry subject to decreasing returns to scale. c. an industry with a rising marginal cost curve. d. an industry in which the prices of one or more inputs are bid up as output expands.28. Along the long-run supply curve, all of the following can vary except a. the level of profits. b. the number of firms in the industry. c. input prices. d. the level of input usage.29. The short-run supply curve for a competitive industry is derived by a. horizontally summing the marginal cost curves for each firm in the industry. b. horizontally summing the average variable cost curves for each firm in the industry. c. vertically summing the marginal cost curves for each firm in the industry. d. none of the above.30. Generally, supply is a. more elastic in the long run than in the short run. b. more elastic in the short run than in the long run. c. more elastic the more firms in the industry. d. more elastic the lower the input prices.