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': 'Corneal ulceration may be caused by injury to which cranial nerve: \nSelect and explain. \nA. Third, B. Fifth, C. Sixth, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Fifth', 'role': 'assistant'}]