This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc. (W.B.C), Subject name: Pathology
[{'content': 'Lymphoplasmacytoid lymphomas may be associated with \nSelect and explain. \nA. IgG, B. IgM, C. IgA, D. IgE', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) IgM(Ref: Robbins 9th/pg 598-602)Lymphoplasmacytic cell proliferation in marrow (Lymphoplasmacytic lymphoma) with secretion of IgM', 'role': 'assistant'}]