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': 'Areas which are not clearly visible in OPG is/are: \nSelect and explain. \nA. Mandibular canine area, B. Coronoid process, C. Anterior body of mandible, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]