13. A study of advertising and the prices of eyeglasses found that the cost of prescription eyeglasses in states that advertising was than in the states that advertising. A) allowed; higher; did not allow B) allowed; lower; did not allow C) did not allow; no different; did allow D) did not allow; lower; did allow 16. Consider an oligopoly with five firms with respective market shares of 60%, 25%, 10%, 3%, and 2%. The HHI for this industry is A) 3600. B) 4334. C) 4338. D) 5000.18. A decision based on the recognition that the actions of others will affect the outcome of the choice, and that takes these actions into account, is a: A) tacit supply curve model. B) playoff payoff. C) perfect competition. D) strategic choice