The correct option is D Specific immuno-modulators stimulate the immuno response of immune system, whereas some other immuno-modulators inhibit it
Immuno-modulators are natural or synthetic substances that help to regulate or normalise the immune system. There are two types of immuno-modulators viz, immuno-suppressants, which cause immuno-suppression of the immune system and immuno-stimulants (immuno-stimulators) which stimulate immune system by inducing or increasing activity of any of its component. Thus the correct answer is option D.