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: Medicine
[{'content': 'The most common cause of hypehyroidism is: \nSelect and explain. \nA. Thyroid hyperplasia, B. Thyroid adenoma, C. Thyroid carcinoma, D. Grave disease', 'role': 'user'}, {'content': "Answer: D \nExplanation: Answer is D (Grave's Disease): Grave's disease is the single most common cause for Hypehyroidism and Thyrotoxicosis.", 'role': 'assistant'}]