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': 'In hyperparathyroidism, all are seen except - \nSelect and explain. \nA. Osteopetrosis, B. Osteoporosis, C. Cysts, D. Brown tumor', 'role': 'user'}, {'content': 'Answer: A \nExplanation: in hyperparathyroidism, osteoporosis occurs but no osteopetrosis in which the bone becomes harder ( Harrison 17 pg 2382)', 'role': 'assistant'}]