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': 'Suggested criteria for the clinical diagnosis of Polycythemia vera (PV) include all except - \nSelect and explain. \nA. Low aerial oxygen saturation, B. Elevated red cell mass, C. Increased counts of cells of all lineages, D. Splenomegaly', 'role': 'user'}, {'content': 'Answer: A \nExplanation: <p>In polycythemia vera,erythrocytosis occurs,so red cell mass increases. It is characterised by pancytosis(increased red cells,granulocytes,platelet).Splenomegaly producing abdominal fullness will be also present.There is increased aerial oxygen saturation in polycythemia vera.</p><p>Reference :Harsh mohan textbook of pathology sixth edition pg no 359.</p>', 'role': 'assistant'}]