You are presented with the quiz "What are capable of dividing into two parts?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "fission takes place when an animal divides into two parts" and "an isotope capable of undergoing fission is called a fissile isotope ". 

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


 

     fissile isotopes      