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: Surgery
[{'content': 'Commonest cause for hyperparathyroidism is ? \nSelect and explain. \nA. Single adenoma, B. Multiple adenomas, C. Single gland hyperplasia, D. Multiple gland Hyperplasia', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Single adenoma", 'role': 'assistant'}]