D
B makes no sense
C makes so sense as variation causes natural selection so if they were all the same natural selection wouldnt happen
A isnt right
the answer is D as the organisms must have some variation in order to be different enough and less/more well adapted to their habitat in order for the less well adapted ones to die- and the more well adapted ones to live and pass on advantageous alleles/genes
        
                    
             
        
        
        
I know that they need air to live
        
                    
             
        
        
        
<span>Both of them are example of Passive transport and Passive processes; If that's the type of answer you are looking for.</span>
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Restriction of blood flow, something is blocking the blood flow, heart has slowed down and is being pushed to hard.
        
             
        
        
        
Answer:
A
Have a great day, and I hope this is right!