According to your text, critics of advertising
a. argue that it lowers consumer prices—and thus results in "less than satisfactory" profits for firms. b. often overrate the positive effect that monopolistic competition can have on the economy. c. who think that a lot of advertising is annoying simply don't know what they're talking about. d. claim that firms use clever ads to persuade consumers to buy whatever the firms want to sell. e. base their evaluation on fears that advertising increases economies of scale.