This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': 'Selenium is an essential component of \nSelect and explain. \nA. Glutathione synthetase, B. Glutathione peroxidase, C. Xanthine dehydrogenase, D. Cytochrome oxidase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]