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': '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: None', 'role': 'assistant'}]