This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
[{'content': 'A common cause of Primary hyperparathyroidism is- \nSelect and explain. \nA. Multiple parathyroid adenomas, B. Solitary parathyroid adenoma, C. Solitary thyroid adenoma, D. Ectopic PTH production', 'role': 'user'}, {'content': 'Answer: B \nExplanation: a single abnormal parathyroid gland is the cause in 80% of patients ( harre 17 pg 2380)', 'role': 'assistant'}]