answer is amount of mass in a certain volume
 
        
                    
             
        
        
        
Your answer would be  <em><u>D. refrigerator coils keeping the refrigerator cold</u></em>
 
        
             
        
        
        
The answer is A because if you want a reliable source of scientific information you should go to an actual scientist at a scientific conference.
        
                    
             
        
        
        
<span>Biology is a very important thing in life it helps us understand what all other living creatures live and what they do to survive and that will lead us to ideas to help us understand about living creatures.</span>