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
[{'content': "Painless effusion in joints in Congenital syphilis are called \nSelect and explain. \nA. Clutton's joint, B. Charcot's joint, C. Barton's joint, D. Chronic osteomyelitis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Painless synovitis at puberty in late congenital syphilis is called clutton's joint.", 'role': 'assistant'}]