Fact 1: Antigens are found on cancer cells and the cells of transplanted organs. Fact 2: Examples of animal organs are kidneys and hearts. Given the two facts above, antigens are found on cancer cells and the cells of transplanted what?

Available choices:
(I) h2o.
(II) kidneys.
(III) genetics.
(IV) operation.
(V) lungs.
(VI) the skin.
(VII) epidermal.
(VIII) alveoli.
Answer:
(II)