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
The immunoglobulin least commonly involved in Multiple Myeloma is: 
Select and explain. 
A. IgG, B. IgM, C. IgA, D. IgD
D: IgD
Answer: D: IgD 
Explanation: Answer is D (IgD) The M component in Multiple Myeloma can be made up of the immunoglobulins IgG, IgM, IgD, IgA, and IgE; light chains alone; or heavy chains alone. IgG Myeloma is the most common form of Multiple Myeloma while Ig D (2%) and IgE (Rare) are the least common.