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
Which of the following is the longest acting oral anticoagulant ? 
Select and explain. 
A. Bishydroxycoumarin, B. Warfarin, C. Acenocoumarol, D. Phenindione
A: Bishydroxycoumarin
Answer: A: Bishydroxycoumarin 
Explanation: Ans. is 'a' i.e., Bishydroxycoumarin Bishydroxycoumarin (Dicumarol) is the longest acting oral anticoagulant. Ethylbiscoumacetate is the shoest acting anticoagulant.