Answer:
Hydrogen 
Explanation:
I think it is showing cellulose cell or DNA as it is inverted 180° for the option there is no option for Phosphodiester bond however I know the answer is hydrogen. 
 
        
             
        
        
        
Enzymes act as catalysts that remain unmodified as they increase the rate of a chemical reaction.
        
                    
             
        
        
        
Mitosis is probably the type of reproduction taking place because it deals with a sperm and an egg it is called (sexual reproduction) 
        
             
        
        
        
These circular DNA molecules are called C: Plasmids
        
             
        
        
        
Your answer would be B. Hope this helped :)<span />