This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
[{'content': 'Following are features of polycythemia rubra vera except - \nSelect and explain. \nA. Increased red cell mass, B. Normal aerial oxygen sturation, C. High leucocyte alkaline phosphatase score, D. None', 'role': 'user'}, {'content': 'Answer: D \nExplanation: <p>Polycythaemia rubra vera results in increased red cell mass,aerial oxygen saturation >92%, & raised neutrophil alkaline phosphatase scores.</p><p>Reference :Harsh mohan textbook of pathology sixth editionpg no 359.</p>', 'role': 'assistant'}]