Please answer.

a. There is so much advertising in monopolistic competition and oligopoly because brand distinction encourages consumer loyalty, which increases profits. price changes are not allowed. there are significant substitution possibilities in these industries. there is product homogeneity in these industries. b. Advertising helps consumers and promotes efficiency by providing information about new products, reducing the number of firms in the industry, and raising average revenue. providing information about new products, increasing sales and output, and lowering average total cost. helping consumers determine their preferences and limiting the number of products firms have to produce. helping consumers determine their preferences and increasing the number of products firms have to produce. c. Which of the following statements is true? When advertising either leads to increased monopoly power or is self-canceling, economic inefficiency results. Excessive advertising can decrease brand loyalty, which encourages new entry into the industry. Persuasive advertising can increase brand loyalty, which encourages new entry into the industry. Persuasive advertising can be important in encouraging new entry into the industry