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
Most common primary malignant bone tumor - 
Select and explain. 
A. Osteosarcoma, B. Osteochondroma, C. Multiple myeloma, D. Osteoclastoma
C: Multiple myeloma
Answer: C: Multiple myeloma 
Explanation: Ans. is 'c' i.e., Multiple myeloma