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': "Surgery indicated for ptosis in Horner's syndrome \nSelect and explain. \nA. Fasanella - servat, B. Levator resection, C. Blaskovics operation, D. Frontalis sling", 'role': 'user'}, {'content': "Answer: A \nExplanation: Fasanella - servat indications:\n\nMild ptosis with good levator action.\nHorner's syndrome.", 'role': 'assistant'}]