<prompt> A patient presents with a painless ulcer on his penis. A Wasserman test is done and is positive. Wasserman reaction is an example of _Complement fixationPrecipitationNeutralizationAgglutination  <response>: 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 