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 is: 
Select and explain. 
A. Osteosarcoma, B. Ewing sarcoma, C. Metastatic carcinoma, D. Multiple MyeLoma
D: Multiple MyeLoma
Answer: D: Multiple MyeLoma 
Explanation: None