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
Osmotic fragility is increased in: 
Select and explain. 
A. Sickle cell anemia, B. Hereditary spherocytosis, C. Thalassaemia, D. Chronic lead poisoning
B: Hereditary spherocytosis
Answer: B: Hereditary spherocytosis 
Explanation: None