This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Microbiology Pa 1 (History, Microscopy, Stains and Structure and Physiology of Bacteria), Subject name: Microbiology
[{'content': "Dark ground microscopy is used for \nSelect and explain. \nA. TPI, B. Kahn's test, C. FTA-ABS, D. VDRL", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Treponema pallidum immobilization (TPI) test Serum of patient with complement and T. pallidum are maintained in a complex medium anaerobically If the antibodies are present, the Treponemes are immobilized when examined under dark ground illumination.', 'role': 'assistant'}]