You are presented with the question "Cells with damaged DNA are more likely to divide when exposed to what?" and the following answer choices: 
- harmful substances
 - apoptotic genes
 - sulfur dioxide
 - a tumor suppressor
 - Electrical energy
 - heat or cold
 - immune system
 - a carcinogen

Now knowing that oncogenes promote the division of cells with damaged DNA and carcinogenic or oncogenic effects cause cancer, choose the best answer.


 

        a carcinogen 