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
Heparin is the most widely used antithrombotic agent. It acts by activating - 
Select and explain. 
A. Plasmin, B. Antithrombin III, C. Fibrinolysin, D. Factor X
B: Antithrombin III
Answer: B: Antithrombin III 
Explanation: Ans. is 'b' i.e., Antithrombin III