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': 'The radiopacity of zygoma is superimposed on roots of: \nSelect and explain. \nA. Premolars, B. 1st and 2nd maxillary molar, C. Maxillary 3rd molar, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The radiopacity of zygoma is usually superimposed on the roots of 1st and 2nd maxillary molars, but not on the roots of 3rd molars.', 'role': 'assistant'}]