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': 'A common cause of Primary hyperparathyroidism is: \nSelect and explain. \nA. Multiple parathyroid adenomas, B. Solitary parathyroid adenoma, C. Adrenal hyperplasia, D. Ectopic PTH production', 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is B (Solitary parathyroid adenoma) : The most common cause of primary hyperparathyroidism is a parathyroid adenoma. A single/solitary abnormal gland is the cause in approximately 80% of patients - Harrison The abnormality of the gland is usually a benign neoplasm or 'adenoma' and rarely a parathyroid carcinoma", 'role': 'assistant'}]