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': 'Action of superior oblique is following except - \nSelect and explain. \nA. Extortion, B. Depression, C. Abduction, D. Intortion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Superior oblique causes intorsion (not extorsion).', 'role': 'assistant'}]