You are presented with the question "Tumors are a collection of cancer what?" and the following answer choices: 
- harmful
 - mutations
 - cells
 - toxins
 - three
 - Mass
 - oncogenes
 - ovaries

Now knowing that cancer cells divide more often than normal cells, and grow out of control and cancer cells, however, grow out of control and develop into a tumor, choose the best answer.


 

   cells      