This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
[{'content': 'Cofactor of carbonic anhydrase is \nSelect and explain. \nA. Molybdenum, B. Zinc, C. Copper, D. Selenium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The active site of most carbonic anhydrases contains a zinc ion; they are therefore classified as metalloenzymes. One of the functions of the enzyme in animals is to interconve carbon dioxide and bicarbonate to maintain acid-base balance in blood and other tissues and to help transpo carbon dioxide out of tissues.', 'role': 'assistant'}]