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
The anticoagulant of choice in pregnancy is : 
Select and explain. 
A. Heparin, B. Warfarin, C. Dicoumarol, D. Phenindione
A: Heparin
Answer: A: Heparin 
Explanation: None