This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Orally acting direct thrombin inhibitor is ? 
Select and explain. 
A. Bivalirudin, B. Ximelagatran, C. Melagatran, D. Argatroban
B: Ximelagatran
Answer: B: Ximelagatran 
Explanation: None