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': 'Which of these structures appears radiopaque? \nSelect and explain. \nA. Maxillary sinus, B. Nasal fossa, C. Nasal septum, D. Mental foramen', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Radiopaque refers to that portion of the radiograph that appears light or white. Radiopaque structures are dense and absorb or resist the passage of the X-ray beam, E.g., Enamel, dentin and bone.\nNasal septum\nOn the panoramic radiograph, it appears as a vertical radiopaque partition that divides the nasal cavity.\nReference: Freny R Karjodkar Oral Radiology Principles and Interpretation 2nd\xa0 edition page no 251', 'role': 'assistant'}]