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': "5% guanethidine is used for \nSelect and explain. \nA. Ptosis, B. Neuro-paralytic keratitis, C. Thyrotoxic ophthalmopathy, D. Homer's syndrome", 'role': 'user'}, {'content': 'Answer: C \nExplanation: C. i.e. Thyrotoxic opthalmopathy', 'role': 'assistant'}]