This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood, Subject name: Pathology
[{'content': 'Which among the following can prevent coagulation of blood: \nSelect and explain. \nA. Calcium oxalate, B. Sodium citrate, C. Sodium iodide, D. Potassium chloride', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans b: (Ref: Guyton 11th edition p466-467)Methods to present blood coagulation in vitro1 Siliconized containers - Present contact activation of platelets & Factor 82 Heparin - Especially is heart lung machine /artificial kidney3 Oxalate compunds - By precipitation of calcium oxalate compounds4 Citrate compounds(Sodium citrate, ammonium citrate, potassium citrate)- By deionization of blood calcium by forming an unionized calcium compound.But remember citrate anticoagulants are superior to oxalate anticoagulants because oxalate is toxic to body; but moderate quantities of citrate can be injected intravenously', 'role': 'assistant'}]