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: Radiology
[{'content': 'In radiograph of non-accidental injury, not seen is \nSelect and explain. \nA. Parietal bone fracture, B. Sternal fracture, C. Costochondral & Rib junction fracture, D. Metaphysis corner fracture', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]