This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
[{'content': 'Which of the following is the mechanism of action of Fondaparinux \nSelect and explain. \nA. Factor Xa inhibition and Thrombin inhibition, B. Factor Xa inhibition, C. Antithrombin inhibitor, D. Thrombin inhibition', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The antithrombotic activity of fondaparinux sodium is the result of antithrombin III (ATIII) mediated selective inhibition of Factor Xa. ref - Harrisons internal medicine 20e pg851', 'role': 'assistant'}]