This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Best confirmatory test for syphilis is \nSelect and explain. \nA. RPR, B. Gram stain, C. VDRL, D. FTA-ABS', 'role': 'user'}, {'content': "Answer: D \nExplanation: FTA-ABS: FTA-absorption test in which the test serum is preabsorbed with sonicate of the Reiter treponemes to eliminate group-specific reactions. FTA-ABS is as specific as the TPI test and is now accepted as a standard reference test. Ref: Textbook of microbiology; Ananthanarayan and paniker's; 10th edition; Pg:382", 'role': 'assistant'}]