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': 'All the following are causes of a painful limp except- \nSelect and explain. \nA. Slipped femoral epiphysis, B. TB of the hip, C. Perthes disease, D. Infantile Coxa Vara', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Infantile (congenital) coxa vara causes painless limp.', 'role': 'assistant'}]