This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
[{'content': '1925. Causes of secondary polycythemia may include \nSelect and explain. \nA. Chronic cor pulmonale, B. Renal carcinoma, C. Cerebellar haemangioblastoma, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Secondary polycythaemia occur due to high altitude,cardiovascular disease ,pulmonary disease with alveolar hypoventilation,heavy smoking,inappropriate erythropoietin(renal cell carcinoma ,hydronephrosis,hepatocellular carcinoma ,cerebellar hemangioblastoma ,massive uterine leiomyoma.). Reference :Harsh mohan textbook of pathology sixth edition pg no 359.', 'role': 'assistant'}]