This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'A patient presents with a painless ulcer on his penis. A Wasserman test is done and is positive. Wasserman reaction is an example of _ \nSelect and explain. \nA. Complement fixation, B. Precipitation, C. Neutralization, D. Agglutination', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Wassermann reaction is an example of a complement fixation test. It is a non specific test for the diagnosis of syphilis. Principle of complement fixation tests: Antigen-antibody complexes fix complement Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition', 'role': 'assistant'}]