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': "M spike on serum electrophorosis is seen in - \nSelect and explain. \nA. Lymphoblastic leukemia, B. Waldenstrom's macroglobulinaemia, C. Alpha-chain disease, D. AIDS", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]