Explanation
The argument suggests that because yoga has been shown to be as effective as an established treatment for lower back pain, doctors should consider it a viable option to discuss with patients. The underlying assumption is that anything as effective as a known treatment should be part of the discussion between doctors and patients.
A. The argument doesn’t rely on there being no better activities; it simply states that yoga is equally effective as another treatment that doctors discuss.
B. (Correct Response) The argument assumes that stretching classes with a physical therapist significantly reduce chronic lower back pain, which justifies discussing yoga because it has been shown to have equivalent benefits.
C. The availability of treatment options is not addressed in the argument.
D. The argument is based on the outcomes of the study comparing the two activities, not on the uniqueness of such studies.
E. The argument does not rely on what many doctors currently discuss; it is about what they should discuss given the new evidence about yoga's effectiveness.
The assumption required for the argument is that the treatment (stretching classes with a physical therapist) yoga is being compared to (and found to be equally effective as) is itself an effective treatment for chronic lower back pain. This supports the notion that if yoga is as effective as an already accepted treatment, it merits discussion, making option B the required assumption.