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 therapy should be monitored with intermittent estimation of : \nSelect and explain. \nA. Bleeding time, B. Prothrombin time, C. PTTK, D. All of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]