This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Plasma Cell Disorders and Multiple myeloma, Subject name: Pathology
M-spike in multiple myeloma is due to? 
Select and explain. 
A. IgM, B. IgA, C. IgG, D. IgD
C: IgG
Answer: C: IgG 
Explanation: In Multiple myeloma laboratory analyses reveal increased levels of Igs in the blood and/or light chains (Bence-Jonesproteins) in the urine. The most common monoclonal Ig ("M protein") is IgG (approximately 55% ofpatients), followed by IgA (approximately 25% of cases).