You are presented with the quiz "What that eventually lead to cell death usually occur in genes that control the cell cycle?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "mutations that lead to cancer usually occur in genes that control the cell cycle" and "free radicals can mutate genes and eventually lead to cancer or cell death". 

So, what's the best answer to the question?


 

 free radicals          