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': 'Superior oblique muscle performs action of: \nSelect and explain. \nA. Intoion, B. Extoion, C. Elevation, D. Medial rotation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Intoion', 'role': 'assistant'}]