This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metastatic Tumors of Bone, Subject name: Orthopaedics
Most common malignancy of bone is? 
Select and explain. 
A. Secondary, B. Multiple myeloma, C. Osteoid osteoma, D. Osteosarcoma
A: Secondary
Answer: A: Secondary 
Explanation: ANSWER: (A) secondaryREF: Apley's 8th edition page 191Most common malignancy of bone: secondariesMost common primary malignancy of bone: multiple myelomaMost common benign tumour of bone: osteochondromaMost common malignancy of bone in children and adolescents: osteosarcomaMost common benign true bone tumor: osteoid osteoma