This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Polycythemia, Subject name: Medicine
[{'content': 'Which is not seen in polycythemia vera : \nSelect and explain. \nA. Increased vitamin B12 binding capacity, B. Increase erythropoietin level, C. Increase RBC count, D. Ocular congestion', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' increased erythropoietin level. In polycythemia Vera increase in erythrocytes occur without any increase in level of erythropoietin. In fact erythropoietin level is decreased due to feedback by increased erythrocytes.", 'role': 'assistant'}]