This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
Dicumarol is a drug that impairs the utilization of vitamin K by the liver. Dicumarol therapy, therefore, would decrease the plasma concentration of which of the following procoagulants 
Select and explain. 
A. Prothrombin, B. Fibrinogen, C. Antihemopilic factor (factor VIII), D. Ac - globulin (factor V)
A: Prothrombin
Answer: A: Prothrombin 
Explanation: Ans. (a) ProthrombinRef: Ganong, 25th ed/p.567Factor II is also called Prothrombin. It is a vitamin K dependent factorWarfarin - acts by inhibiting Vitamin K Epoxide reductase (VKORC1)