This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Molybdenum is a constituent of: \nSelect and explain. \nA. Xanthine oxidase, B. Cytochrome oxidase, C. Phosphofructokinase, D. Carbonic anhydrase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Molybdenum containing enzymes include aldehyde oxidase, sulfite oxidase and xanthine oxidase.', 'role': 'assistant'}]