When a person receives an organ transplant, they will also typically take drugs that suppress their immune system so it doesn't attack the new organ. Which of the following best explains why an organ recipient's immune system will attack a donated organ?
a) The donated organ has cytokines, which the body recognizes as non-self.
b) The donated organ has antigens, which the body recognizes as non-self.
c) The donated organ has histamines, which the body recognizes as non-self.
d) The donated organ has T cells, which the body recognizes as non-self.