Answer:
Mark pathogenic cells for destruction. (Ans. B)
Explanation:
Antibodies are generated by the plasma cells, and once these secreted, they attach quickly to the surface of the toxin and stop the toxin from infecting the normal body cell by blocking key extracellular sites.
Antibodies also help to mark pathogens for destruction by the help of macrophages or neutrophils and they are known as phagocytic cells because they are highly excited to macro-molecules complexed with antibodies. 
 
        
             
        
        
        
I'd say your answer is, 
C. the attraction and bonding of ions with equal opposite charges.
        
             
        
        
        
DNA/fingerprints are all unique, therefor it is easy to match a fingerprint to a person thus they use this mechanism in criminal investigations because only one person woul have matching DNA to the prints on the scene, and that is the criminal.
Hope this helps :)
 
        
             
        
        
        
Answer:
ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.