You are presented with the quiz "Cells secrete acids and bases to maintain what?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "cells secrete acids and bases to maintain the proper pH for enzymes to work" and "most human enzymes work at a optimal pH of 7.4, but other enzymes work at many different pH ranges". 

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


 

     most human enzymes      