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: Medicine
[{'content': 'Alpha chain disease is detected by - \nSelect and explain. \nA. M component in serum, B. Jejunal biopsy, C. Light chain in lumen of jejunum, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]