Physician: In an experiment, 50 patients with chronic back pain were divided into two groups. Small magnets were applied to the backs of one group; the other group received no treatment. Most of the patients in the first group, but very few in the second group, reported magnetic fields are probably effective at relieving some back pain.
What this question is testing
Your task
Find the choice that makes the argument's conclusion less likely to be true.
Common trap
Answers that look negative but attack a claim the argument never relied on.
Winning move
Find the assumption the argument depends on, then pick the choice that undermines it.
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