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': 'Cobalt forms a component of which vitamin \nSelect and explain. \nA. Biotin, B. Vitamin B12, C. Vitamin A, D. Tocopherol', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Vitamin B12 is a corrinoid, i.e. cobalt-containing compound possessing the corrin ring.', 'role': 'assistant'}]