The answer is C : Unicellular bacteria
        
                    
             
        
        
        
The lining of the back of eye containing two types of photoreceptor cells - rods - sensitive to dim light and black and white - and cones - sensitive to colour. A small area called the fovea in the middle of the retina has many more cones than rods.
        
                    
             
        
        
        
Setting up wildlife preserves where no hunting is allowed. You’re making it possible for species to flourish, increasing biodiversity.