Answer:
would the answer be hydrogen ion gradient 
 
        
             
        
        
        
Light speed in water is 2.25 times 10^5 m/s so the index of refraction is higher than the index of refraction of light in a vacuum which is 1.0. (speed in vacuum for light is 300,000 km/s) 
Index of refraction of light in water is 3.0 time 10^5 m/s divided by 2.25 times 10^5 m/s = 1.33.
Hope this is what you wanted.
        
                    
             
        
        
        
Answer:
Eosinophils 
Explanation:
These are type of White blood cells W.B.C ,present almost 2% of white cells . About twice the size of red blood cells , Nucleus is bi lobed . They are often used for parasite attack , Inactivate inflammation and production of substances . 
 
        
             
        
        
        
Should be A. Species have changed over time.