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': 'Pancytopenia may occur in the following except - \nSelect and explain. \nA. Megaloblastic anaemia, B. Severe iron-deficiency anaemia, C. Hypoplastic anaemia, D. Paroxysmal nocturnal haemoglobinuria', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]