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 with cellular marrow is seen in: \nSelect and explain. \nA. PNH, B. G6PD deficiency, C. Acquired aplastic anemia, D. Thalassemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (PNH) Amongst the options provided PNH is the single best answer of choice.', 'role': 'assistant'}]