【单选题】A researcher 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 rese...
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 system.
C.
People with high immune-system activity cannot develop mental illness.
D.
Mental illness does not cause people's immune-system activity to decrease.
E.
Psychological treatment of mental illness is not as effective as is medical treatment.