The answer is C because the load shouldnt be greater than the effort, it isnt usually, but my best answer to you would be C 
        
             
        
        
        
Ten (10%). when an animal eats the plant, 10% of it will be used.
        
             
        
        
        
Solar planet in an undiscovered solar planet. With no other living organisms at its surroundings.
        
                    
             
        
        
        
I believe it was The Continental Drift Theory , i could be wrong 
        
             
        
        
        
Answer:
<h2>Billions</h2>
But Talking about our solar system, we've 8 Planets