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: Pathology
What is the best prognostic indicator of multiple myeloma at the time of diagnosis ? 
Select and explain. 
A. Number of myeloma cells in the marrow, B. Beta 2 microglobulin, C. Alkaline phosphatase level, D. Hypercalcemia
B: Beta 2 microglobulin
Answer: B: Beta 2 microglobulin 
Explanation: Ans. is 'b' i.e., Beta-2 Microglobulins o Serum /32 microglobulin is the single most powerful predictor of survival and can substitute for staging.P2 Microglobulin level :< .004g/L Median survival of 43 months.> .004 g/L Median survival of only 12 months.