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
[{'content': 'Warfarin act by \nSelect and explain. \nA. Inhibiting the activation of vitamin K dependent factors, B. Inhibiting thrombin indirectly through antithrombin III, C. Directly inhibiting thrombin, D. Inhibiting Gp IIb/IIIa', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]