You are presented with the quiz "What does breathing help balance acidity levels?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "blood pH may become unbalanced if the rate of breathing is too fast or too slow" and "breathing is regulated to keep as normal as possible arterial blood pH and PO2". 

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


 

 blood          