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: Ophthalmology
[{'content': 'All of the following are pas of optic nerve except \nSelect and explain. \nA. Intraorbital Pa, B. Intracanlicular Pa, C. Cisternal Segment, D. Intra cavernal Pa', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Answer- D. Intra cavernal PaOptic nerve is about 47-50 mm in length and can be divided into 4 pas :Intraocular pa (l mm)Intraorbital pa (30 mm)Intracanalicular pa (6-9 mm)Intracranial pa (10 mm)', 'role': 'assistant'}]