After being subjected to clinical tests like those used to evaluate the effectiveness of prescription drugs, a popular nonprescription herbal remedy was found to be as effective in treating painful joints as is a certain prescription drug that has been used successfully to treat this condition. The manufacturer of the herbal remedy cited the test results as proof that chemical agents are unnecessary for the successful treatment of painful joints. The test results would provide the proof that the manufacturer claims they do if which one of the following is assumed? ['The prescription drug treats the discomfort associated with painful joints without eliminating the cause of that condition.', 'People are likely to switch from using prescription drugs to using herbal remedies if the herbal remedies are found to be as effective as the prescription drugs.', 'The researchers who analyzed the results of the clinical testing of the herbal remedy had also analyzed the results of the clinical testing of the prescription drug.', 'The herbal remedy contains no chemical agents that are effective in treating painful joints.']