This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'Thrombomodulin-thrombin complex prevents clotting because \nSelect and explain. \nA. Thrombomodulin inhibits prothrombin activator, B. Thrombomodulin-thrombin complex activities anti-thrombin III, C. The binding of thrombomodulin with thrombin removes thrombin and also activities a plasma protein C which inactivates activated factors V & VIII, D. Thrombomodulin-thrombin complex activates heparin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The endothelium of the blood vessels also plays an active role in preventing the extension of clots. All endothelial cells except those in the cerebral microcirculation produce thrombomodulin, a thrombin-binding protein, on their surfaces. In circulating blood, thrombin is a procoagulant that activates factors V and VIII, but when it binds to thrombomodulin, it becomes an anticoagulant in that the thrombomodulin-thrombin complex activates protein C. Activated protein C (APC), along with its cofactor protein S, inactivates factors V and VIII and inactivates an inhibitor of tissue plasminogen activator, increasing the formation of plasmin.Ref: Ganong&;s Review of medical physiology 25th edition. Page: 565', 'role': 'assistant'}]