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
Anticoagulant  used for osmotic fragility test 
Select and explain. 
A. EDTA, B. 3.2 % Trisodium citrate, C. Heparin, D. Warfarin
C: Heparin
Answer: C: Heparin 
Explanation: Heparin - osmotic fragility test.
EDTA - Blood cell counts.
3.2% trisodium citrate  - ESR, platelet studies.