Answer:
The last option provided in the image 
Explanation:
REM
 
        
             
        
        
        
The answer is one mystery that still remains unsolved is why we yawn.
and another theory is that when you yawn it sends oxygen to the brain causing your body to be able to stay awake, hence when you are tired and need to stay awake you yawn a lot.
        
             
        
        
        
Answer:
u can take some ideas from these pictures 
hope this helps!