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
A 50-year-old patient presents with a lesion in the midline involving the sacrum. It is found to be sclerotic. What is the most probable diagnosis - 
Select and explain. 
A. Metastatic, B. Chordoma, C. Osteosarcoma, D. Chondrosarcoma
B: Chordoma
Answer: B: Chordoma 
Explanation: Sclerotic lesion involving midline in the sacrum is likely to be chordoma.
It occurs most commonly at either end of notochord(midline) in following locations


Sacrococcygeal region
Clivus
Suprasellar region