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': 'Dicumarol is a drug that impairs the utilization of vitamin K by the liver. Dicumarol therapy would decrease the plasma concentration of which of the following procoagulants \nSelect and explain. \nA. Prothrombin, B. Fibrinogen, C. Factor VIII, D. Factor V', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Factor II is also called as Prothrombin, it is a vitamin K dependent clotting factor. Warfarin acts by inhibiting Vitamin K Epoxide Reductase Complex(VKORC) subunit 1 Ref: Ganong 25th ed/page 567', 'role': 'assistant'}]