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 superior oblique muscle is supplied by - \nSelect and explain. \nA. 3\nrd \ncranial nerve, B. 4\nth\n cranial nerve, C. 5\nth\n cranial nerve, D. 6\nth \ncranial nerve', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Superior oblique is supplied by 4th (trochlear) nerve.', 'role': 'assistant'}]