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 therapy should be monitored with intermittent estimation of: \nSelect and explain. \nA. Bleeding time, B. aPTT, C. Prothrombin time, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: aPTT is maintained 1.5 - 2 times the normal mean aPTT value. Clotting time is maintained at 1.8 - 2.5 times the normal mean aPTT value. From medical pharmacology padmaja 4th edition Page no 335', 'role': 'assistant'}]