Final answer:
The characteristic 'firms are price takers' is not associated with monopolistic competition but with perfect competition.
The correct answer is option b firms are price takers.
Step-by-step explanation:
The characteristic that is not a part of monopolistic competition is 'b firms are price takers.' This option is associated with perfect competition, where many sellers offer identical products, allowing no single firm to influence market prices. In monopolistic competition, firms are not price takers; although there are many sellers and products are differentiated, each firm has some control over its product's price due to product differentiation.
Some characteristics of monopolistic competition include a large number of sellers (option a), differentiated products that are distinct from competitors' offerings (option c), and relatively free entry into the market (option d).