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': 'Heparin induced thrombocytopenia is due to antibodies against \nSelect and explain. \nA. PF - 1, B. PF - 2, C. PF - 3, D. PF - 4', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Antibodies against platelet factor-4 (PF-4) causes aggregation of platelets and thrombosis, thus leads to thrombocytopenia.', 'role': 'assistant'}]