This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2019, Subject name: Pharmacology
Which of the following is an oral direct thrombin inhibitor? 
Select and explain. 
A. Dabigatran, B. Rivaroxaban, C. Warfarin, D. Lepirudin
A: Dabigatran
Answer: A: Dabigatran 
Explanation: ORAL: Direct thrombin inhibitor- Dabigatran, Ximelagatran Direct factor Xa inhibitors Apixaban Rivaroxaban Edoxaban Betrixaban Warfarin inhibits Epoxide Reductase thus ?Activated Vit k - ? decreased gamma carboxyglutamate residue ?functionality of factor 2,7,9,10 Lepirudin: - Parenteral Direct Thrombin Inhibitor