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': "An exaggerated smile line seen in OPG is due to \nSelect and explain. \nA. Patient's chin positioned too high, B. Patient's head positioned too far back, C. Patient's chin positioned too low, D. Patient's head positioned too forward", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]