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 Q:  A research discovered that people who have low levels of  immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.

The research's conclusion depends on which of the following assumptions

A. High immune-system activity protects against mental illness better than normal immune-system activity does.

B Mental illness is similar to physical disease in its effects on  body systems

C people with high immune-system activity can't develop mental illness.

D mental illness does not cause people's immune-system activity to decrease.

E psychological treatment of mental illness if not as effective as is medical treatment.

D?

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