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: Unknown
[{'content': 'This disease is \nSelect and explain. \nA. Osteochondrosis of the lunate, B. Osteochondrosis of the navicularq, C. Tuberculosis of the scaphoid, D. Syphilitic dactylitis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Osteochondrosis of the tarsal navicular (Kohler's disease) is characterised by aseptic necrosis of the Navicular bone causing a painful limp in a child usually 4-10 years of age.", 'role': 'assistant'}]