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': 'Paranasal sinus which can be visualized best on a occipito-frontal view is: September 2009 \nSelect and explain. \nA. Frontal sinus, B. Ethmoidal sinus, C. Sphenoid sinus, D. Maxillary sinus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A: Frontal Sinus Caldwell-Luc/ occipito-frontal view shows: Frontal sinus (Best visualization) Superior orbital fissure Superior marginof orbit and lamina papyracea Foramen rotundum Maxillary and ethmoid sinus', 'role': 'assistant'}]