This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematology, Subject name: Pharmacology
[{'content': 'Heparin acts as an anticoagulant by:- \nSelect and explain. \nA. Activating antithrombin III, B. Inactivating antithrombin III, C. Activating thrombin, D. Activating factor Xa', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Heparin acts an anticoagulant by activating antithrombin III and thus inactivating thrombin and factor Xa. Heparin displaces lipoprotein lipase enzyme from the endothelial wall. Other glycosaminoglycans uses are: Danaparoid is an anticoagulant.', 'role': 'assistant'}]