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
Which of the following is not a benign bone tumor - 
Select and explain. 
A. Osteoid osteoma, B. Chondroma, C. Enchondroma, D. Chordoma
D: Chordoma
Answer: D: Chordoma 
Explanation: Chordoma is a malignant tumor arising from notochordal remnants.