This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal System, Subject name: Radiology
[{'content': 'Investigation of choice to diagnose congenital hip dislocation in neonates? \nSelect and explain. \nA. Plain radiographs, B. US, C. CT, D. MRI', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans BIn neonates the femoral head is cartilaginous and not ossified hence it cannot be identified on radiographs but well demonstrated on USG. Also the Graf's classification using Alpha and Beta angles are very definitive in assessment and can be readily calculated on USG.", 'role': 'assistant'}]