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: Orthopaedics
[{'content': "Osteonecrosis of femoral head seen in -a) Sickle cell diseaseb) Gaucher's diseasec) Polycythemiad) Hyperparathyroidisme) Fracture \nSelect and explain. \nA. bcde, B. abcd, C. acde, D. abce", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Sickle cell anemia and polycythemia can cause AVN.', 'role': 'assistant'}]