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, answer the question "antigens are found on cancer cells and the cells of transplanted what?" with the following options: 
- h2o
 - kidneys
 - genetics
 - operation
 - lungs
 - the skin
 - epidermal
 - alveoli


 

  kidneys       