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
[{'content': 'Zinc is a component of the following except \nSelect and explain. \nA. Hexokinase, B. Carbonic anhydrase, C. Insulin, D. Carboxypeptidase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Repeated question', 'role': 'assistant'}]