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: Pathology
Preservative used in coagulation study is - 
Select and explain. 
A. Calcium citrate, B. EDTA, C. Sodium bromide, D. Thrombin
B: EDTA
Answer: B: EDTA 
Explanation: Answer- B. EDTACommonly used anti coagulants are-EDTAHeparinSodium citrateOxalatesSodium fluorideSodium iodoacetate