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': 'Anticoagulant  used for osmotic fragility test \nSelect and explain. \nA. EDTA, B. 3.2 % Trisodium citrate, C. Heparin, D. Warfarin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Heparin - osmotic fragility test.\nEDTA - Blood cell counts.\n3.2% trisodium citrate\xa0 - ESR, platelet studies.', 'role': 'assistant'}]