This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, Subject name: Orthopaedics
[{'content': 'Brown tumour is seen in \nSelect and explain. \nA. Hyperparathyroidism, B. Hypoparathyroidism, C. Hypothyroidism, D. Hypehyroidism', 'role': 'user'}, {'content': "Answer: A \nExplanation: Brown's tumour: This is an expansile bone lesion, a collection of osteoclasts. It commonly affects the maxilla or mandible, though any bone may be affected. Commonly seen in Hyperpathyroidism Ref: Maheshwari 6e pg 313.", 'role': 'assistant'}]