Sentence Correction

While the immune system helps the human body's trying to defend itself from a virus or disease that is harming it certain immunodeficiency
disorders like AIDS attack the immune system itself and disable its healing mechanisms.
(A) body's trying to defend itself from a virus or disease that is harming it
(B) body's tries to defend itself from a virus or disease harming it
(C) body to try to defend itself from a virus or disease that harm it
(D) body to attempt to try to defend itself from a virus or disease that is harming it
(E) body to try to defend itself from a virus or disease that is harming it