This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: nutrition and digestion, Subject name: Biochemistry
Zinc is a component of the following except 
Select and explain. 
A. Hexokinase, B. Carbonic anhydrase, C. Insulin, D. Carboxypeptidase
A: Hexokinase
Answer: A: Hexokinase 
Explanation: Repeated question