Gravitational waves are ripples in spacetime. They are created whenever objects with mass move. Hope this helps :)
        
             
        
        
        
Your answer is hypothesis i think. There were no given answer choices so i went with what i think youre asking.
        
                    
             
        
        
        
Hello! The answer is false. 
It is actually the opposite. The notochord is a primitive axial skeleton, and in humans, it disappears. It eventually becomes part of the vertebral column, which is the backbone that we have today.
Hope this helps!
 
        
             
        
        
        
Answer:
the shape of white blood cells
 
        
                    
             
        
        
        
Answer:
pets can help boost your mood 
Explanation:
if you do not have any pets you could have slight depression if there is no one to cheer you up such as your companion