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': 'In cavernous sinus thrombosis, first nerve to be affected is: September 2012 \nSelect and explain. \nA. 6th, B. 5th, C. 4th, D. 3rd', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A i.e. 6th', 'role': 'assistant'}]