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': 'The only cranial nerve which supplies a contralateral muscle is- \nSelect and explain. \nA. Third, B. Fourth, C. Seventh, D. Tenth', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "It is important to remember that cranial nerves never cross (except for one exception, the 4th cranial nerve) and clinical findings are always on the same side as the cranial nerve involved".\n—Clinical neurology', 'role': 'assistant'}]