You are presented with the quiz "Which bodily system excretes a substance commonly used in drug testing?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "urine is the liquid waste product of the body that is excreted by the urinary system" and "urine tests detect drugs used up to 36 hours before a given urine collection". 

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


 

  urinary system         