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 13- thalassemia - \nSelect and explain. \nA. Excess chain, B. No 13 chain, C. No chain, D. Normal chains', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., No 13 chain", 'role': 'assistant'}]