You are presented with the question "what can cause a tumor to form?" and the following answer choices: 
- parasites
 - cancer
 - respiration
 - digestion
 - pesticide
 - radiation
 - ovaries
 - weathering

Now knowing that cells that divide uncontrollably may form a tumor, or abnormal mass of cells and cancer begins when a cell begins dividing uncontrollably, choose the best answer.


 

  cancer       