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
[{'content': '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 - \nSelect and explain. \nA. Metastatic, B. Chordoma, C. Osteosarcoma, D. Chondrosarcoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sclerotic lesion involving midline in the sacrum is likely to be chordoma.\nIt occurs most commonly at either end of notochord(midline) in following locations\n\n\nSacrococcygeal region\nClivus\nSuprasellar region', 'role': 'assistant'}]