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': "The commonest cause of limp in a child of seven years is - \nSelect and explain. \nA. T.B. hip, B. C.D.H, C. Perthe's disease, D. Slipped upper femoral epiphysis", 'role': 'user'}, {'content': "Answer: C \nExplanation: The most common cause of limp in a child between 3-10 years is transient synovitis of hip.\nHowever, among the given options Perthe's disease is the best answer as Perthes disease is the second most common cause of limp in a child between 5-10 years.", 'role': 'assistant'}]