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: Orthopaedics
A most common cause of bone malignancy- 
Select and explain. 
A. Secondaries, B. Osteosarcoma, C. Ewing's sarcoma, D. Osteoclastoma
A: Secondaries
Answer: A: Secondaries 
Explanation: Metastatic bone disease is the commonest malignancy of bones and is much more common than primary bone tumours