You are presented with the question "What can lead to cancer in genes that control the cell cycle?" and the following answer choices: 
- radiation
 - adding heat
 - competition
 - ice
 - bacteria
 - air
 - carcinogens
 - Smoking

Now knowing that mutations that lead to cancer usually occur in genes that control the cell cycle and many carcinogens are capable of causing gene mutations, choose the best answer.


 

       carcinogens  