You are presented with the question "What can trigger immune response?" and the following answer choices: 
- harmful substances
 - Transplanted organs
 - desire
 - an area swollen with pus
 - death
 - pain
 - colors of the spectrum
 - Contaminated wounds

Now knowing that antigens are found on cancer cells and the cells of transplanted organs and anything that can trigger an immune response is called an antigen, choose the best answer.


 

  Transplanted organs       