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 statements is not true for heparin - 
Select and explain. 
A. Acts by activating anti-thrombin III, B. Protamine sulphate antagonizes its action, C. Requires aPTT monitoring in patient, D. Has only in vivo anticoagulant action
D: Has only in vivo anticoagulant action
Answer: D: Has only in vivo anticoagulant action 
Explanation: Ans. is 'd' i.e., Has only in vivo anticoagulant action o Heparin has action both in vitro and in vivo.