<prompt> Complement Fixation test is:WIDALCoombs testWassermann reactionVDRL  <response>: The complement fixation test CFT was extensively used in syphilis serology after being introduced by Wasserman in 1906. However, there is now a trend to replace the CFT with the simple flocculation tests. Although CFT is considered to be a relatively simple test, it is a very exacting procedure because 5 variables are involved. In essence the test consists of two antigen-antibody reactions, one of which is the indicator system. REF: ROBBINS pathology 10th edition 