17. Which of the following pairs illustrates the two extreme examples of market structures? a competition and oligopoly b. competition and monopoly c. monopoly and monopolistic competition d. oligopoly and monopolistic competition 18. The two types of imperfectly competitive markets are a monopoly and monopolistic competition. b. monopoly and oligopoly. c. monopolistic competition and oligopoly. d. monopolistic competition and cartels. 19. The commercial jetliner industry consisting of Boeing and Airbus would best be described as a (an) a. perfectly competitive market. b. monopolistically competitive market. c. oligopoly. d. monopoly. 20. One way in which monopolistic competition differs from oligopoly is that a. there are no barriers to entry in oligopolies. b. in oligopoly markets there are only a few sellers. c. all firms in an oligopoly eventually eam zero economic profits. d. strategic interactions between firms are rare in oligopolies. 21. If firms in a particular market similar or sell identical products, then the market is (0) perfectly competitive. (1) a b. C. d. monopolistically competitive. an oligopoly. (1) or (ii) only (ii) or (iii) only (1) or (iii) only (i) only 22. If firms in a monopolistically competitive market are incurring economic losses, which of the following scenarios would best de- scribe the change remaining firms would face as the market ad- justs to the long-run equilibrium? a a downward shift in the marginal cost curve for each firm b. an upward shift in the marginal cost curve for each firm C. a decrease in demand for each firm. d an increase in demand for each firm 26 27 28. [Tab