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
Corneal ulceration may be caused by injury to which cranial nerve: 
Select and explain. 
A. Third, B. Fifth, C. Sixth, D. All of the above
B: Fifth
Answer: B: Fifth 
Explanation: Ans. Fifth