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': 'All of the following are causes of pancytopenia with cellular bone marrow except: \nSelect and explain. \nA. Paroxysomal noctural hemoglobinuria, B. Dyskeratosis congenita, C. Megaloblastic anemia, D. Hairy cell leukemia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Answer is B (Dyskeratosis congenita) Dyskeratosis congenita is associated with Pancytopenia and a hypocellular marrow.', 'role': 'assistant'}]