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': 'Avascular necrosis is seen in -a) Sickle cell diseaseb) Thalassemiac) Polycythemiad) Hyperparathyroidism \nSelect and explain. \nA. a, B. bc, C. ac, D. b', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Sickle cell anemia and polycythemia can cause AVN.', 'role': 'assistant'}]