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': "Most common cause of hypercalcemic crisis is: \nSelect and explain. \nA. Carcinoma breast, B. Parathyroid hyperplasia, C. Parathyroid adenoma, D. Paget's disease", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Carcinoma Breast): The most common cause of hypercalcemic crisis is malignancy. Hypercalcemic crisis due to primary hyperparathyroidism is rare - Surgical Oncology 1St (2003)/601 Amongst the options provided, carcinoma breast is the single best answer of choice. Hypercalcemic Crisis Hypercalcemic crisis refers to the presence of severe hypercalcemia and is defined arbitrarily as a total calcium > 14mg/d1 (> 3.5 mmo1/1) The most common cause of hypercalcemic crisis is malignancy and the most common cause is believed to be', 'role': 'assistant'}]