Manufacturers sometimes discount the price of a product to retailers for a promotion period when the product is advertised to consumers. Such promotions often result in a dramatic increase in amount of product sold by the manufacturers to retailers. Nevertheless, the manufacturers could often make more profit by not holding the promotions.
Which of the following, if true, most strongly supports the claim above about the manufacturers’ profit?
profit=R-C R=P*Q。Q不变（零售价不变，需求不变） P减少（有折扣P减少），所以R减少Profit减少