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: Microbiology
[{'content': 'Investigation of choice for detection of syphillis in a patient after 2 course of complete therapy - \nSelect and explain. \nA. FTA ABS, B. VDRL, C. TPI, D. Dark ground microscopy', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]