You are presented with the quiz "what is it when a gill converts from oxygen in water into oxygen in blood?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "breathing is when a gill converts from oxygen in water into oxygen in blood" and "many people confuse breathing with respiration, but breathing is just the first step of respiration". 

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


 

    first step of respiration       