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': 'A 59-year-old male came with Hb 18.0 gm/dl on three occasions. The resident doctor wants to exclude Polycythemia Vera. Which of the following is the most relevant investigation - \nSelect and explain. \nA. Hematocrit, B. Total leukocyte count, C. Red cell mass, D. Reticulocyte count', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]