18. Which of the curves is most likely to characterize the short-run average total cost curve of the biggest factory? A. ATCA b. ATCB c. ATCC d. ATCD 19. Which curve represents the long-run average total cost? A. ATCA b. ATCB c. ATCC d. ATCD 20. Assuming the firm is currently operating on ATCB, what options does it have if it wants to change its level of automobile production over the next couple of weeks? A. It can operate at any level of output as long as it stays on ATCB. B. It can operate at any level of output between points M and N. c. It can operate at any level of output, as long as it stays on ATCD. D. The firm has no options.