I believe it is the retina that changes shape to focus on distant objects.
        
                    
             
        
        
        
Answer: In an ionic bond the valence electrons are transferred from the metal only to the neighboring nonmetal, but in metallic bonding the valence electrons of each atom/ion are free to move or float around within the entire metal solid.
Explanation:
 
        
             
        
        
        
Answer:
Humus
Explanation:
Also known as the uppermost layer of soil, that's for making soil more fertile due to its organic content. 
 
        
                    
             
        
        
        
Its most likely B because its Skeleton is its structure (?)
        
                    
             
        
        
        
It gets transferred through out animals
hope this helps