Here's an ad: As far as fistula pain is concerned, three quarters of hospitals use "Novex" analgesics for patients. Therefore, if you want to treat fistula most effectively, choose "Novex ". Which of the following, if true, would most weaken the argument for the ad? ['Some brand-name analgesics can reduce other pain in addition to fistula pain.', 'Many hospitals that do not normally use "Novex" also use "Novex" for those who are not used to the medicines commonly used in hospitals.', 'Many drug manufacturers sell these products to hospitals at the lowest price they are willing to offer, thereby increasing sales of their products.', 'Unlike other brand-name analgesics, without a doctor\'s prescription, you can also buy "Novex" in pharmacies.']