1. Why is there so much advertising in monopolistic competition and oligopoly? How does such advertising help consumers and promote efciency? Why might it be excessive at times? What is the difference between monopolistic competition and oligopoly? What is the difference between oligopoly and monopoly? [Which type of market structure do you think the following products are in (and why): a. Haircuts and salon services. b. New home construction. c. Shampoo. d. Internet services