GMAT Critical Reasoning (CR) | Re: A researcher discovered that people who have low levels of

This is one of the best OG CR question.

Here the main point is,
mental illness is prevalant not only in lower immune-system but also in higher or normalimmune-system .

But Higher or Normal immune-system has less level of mental illness than Lower immune system.

So, good(normal and high) Immune system help to avoid/reduce Mental illness.

Thus, if we reduce the immunity is reduced due to Mental illness , it proves the research is wrong,therefore the assumption is it does not.
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