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: Pharmacology
[{'content': "Guanethidine is used in the treatment of which of the following condition? \nSelect and explain. \nA. Thyrotoxic ophthalmopathy, B. Ptosis, C. Bell's palsy, D. Horner's syndrome", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Guanethidine (10%) eye drops is useful in decreasing lid retraction in Thyrotoxic ophthalmopathy. It is an adrenergic neuron blocker which acts by inhibiting the release of noradrenaline in response to nerve stimulation.', 'role': 'assistant'}]