8. Refer to the advertising expenditure rule when answering the following. a. Show that a perfectly competitive firm will not spend on advertising. b. Show that as a market's concentration increases, firms spend more on advertising. C. Show that a firm's profit-maximizing advertising-to-sales ratio (TEA/TR) is a constant proportion of its profit-maximizing markup; i.e. TE, / TR = E, x (P-MC)/ P]. d. Independent of your answer to (c), show that a firm's profit-maximizing advertising-to-sales ratio is equal to the firm's elasticity of price with respect to advertising, EPA = %AP/%AA. Note: by comparing the profit-maximizing advertising rule given in class and the one given in (d), you should now be aware that advertising has both quantity and price effects and be able to discuss how these affect the profit-maximizing advertising-to-sales ratio