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
4 year old child complains of painful  limb, the likely cause 
Select and explain. 
A. Poliomyelitis, B. Infantile coxa vara, C. Perthe's disease, D. CTEV
C: Perthe's disease
Answer: C: Perthe's disease 
Explanation: None