C is correct. the rest is either about food webs or about both food webs and food chains. 
        
             
        
        
        
Answer: A positron or antielectron is the antimatter counterpart to an electron. A positron has the equal or same mass as an electron and a spin of 1/2, but it has an electrical charge of +1.
Explanation:
 
        
             
        
        
        
<span>Because the bases can be arranged in many different combinations</span>