You are presented with the quiz "When do platyhelminthes reproductive organs develop?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "adult worms go through a major transformation to develop reproductive organs" and "marine flatworms belong to a major group of worms called the Platyhelminthes". 

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


 

 when they become adults          