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: Pathology
[{'content': 'Barr body was first detected in: DNB 08 \nSelect and explain. \nA. Buccal mucosa, B. Brain, C. Liver, D. Skin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Brain', 'role': 'assistant'}]