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

Now knowing that antigens are found on cancer cells and the cells of transplanted organs and examples of animal organs are kidneys and hearts, choose the best answer.


 

  kidneys       