Answer:
search it in Google or any other browser
 
        
             
        
        
        
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:
b it states the main idea that is what I got told
 
        
             
        
        
        
Pretty sure the answer would be C.