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': 'A 50 year old male patient complains of heaviness of face, headache and blocked nose. Patient gives history of chronic sinusitis. Waters view x-ray was taken. If the patient’s mouth is open during x-ray, the sphenoid sinus is seen superimposed over- \nSelect and explain. \nA. Nasal bone, B. Coronoid process, C. Maxillary sinus, D. Palate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Waters view-\xa0\nThe image receptor is placed in front of the patient and perpendicular to the midsagittal plane. The patient’s head is tilted upward\xa0so\xa0 that\xa0 the\xa0 canthomeatal\xa0 line\xa0 forms\xa0 a\xa0 37-degree\xa0 angle\xa0 with\xa0 the\xa0image receptor. If the patient’s mouth is open, the sphenoid sinus is seen superimposed over the palate.\nWhite and Pharoah, Oral radiology, ed 7th, pg-161', 'role': 'assistant'}]