Which is the anti - coagulant substance in blood?
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Fibrinogen
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Heparin
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Thrombin
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Globin
B
Correct answer
Explanation
Heparin is a natural anticoagulant substance found in blood, produced by mast cells and basophils. It prevents blood clotting by inhibiting thrombin. Fibrinogen and thrombin are actually involved in blood clotting (coagulation), not preventing it. Globin is a protein component of hemoglobin and unrelated to clotting.