This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
Which antibody is commonly elevated in walder strom macroglobinemia ?- 
Select and explain. 
A. IgG, B. IgA, C. IgM, D. IgD
C: IgM
Answer: C: IgM 
Explanation: Waldenstrom's macroglobulinemia (WM), also known as lymphoplasmacytic lymphoma, is a type of cancer affecting B cells, a type of white blood cell. The main attributing antibody is immunoglobulin M (IgM). WM is an "indolent lymphoma" (i.e., one that tends to grow and spread slowly). It is a type of lymphoproliferative disease, which shares clinical characteristics with the indolent non-Hodgkin lymphomas.