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': 'Osmotic fragility is increased in: \nSelect and explain. \nA. Sickle cell anemia, B. Hereditary spherocytosis, C. Thalassaemia, D. Chronic lead poisoning', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]