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': 'In sickle cell anaemia defect is in which chain ? \nSelect and explain. \nA. a-chain, B. B-chain, C. Both the chains, D. None of these', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., n-chain", 'role': 'assistant'}]