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': 'An example of a preventive antioxidant is: \nSelect and explain. \nA. Catalase, B. Tocopherol, C. Superoxide dismutase, D. Urate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Antioxidants fall into two classes:\n\nPreventive antioxidants, which reduce the rate of chain initiation.\xa0 ex: Catalase and other peroxidases such as glutathione peroxidase.\nChain-breaking antioxidants, which interfere with chain propagation.\xa0 ex: Superoxide Dismutase, Uric Acid, Vitamin E (Most powerful).\n\nKey Concept:\nCatalase falls into preventive anti-oxidants which reduce the rate of chain initiation.\nRef : Harper’s illustrated biochemistry, 31st edition.', 'role': 'assistant'}]