This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
[{'content': 'Complement Fixation test is: \nSelect and explain. \nA. WIDAL, B. Coombs test, C. Wassermann reaction, D. VDRL', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 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', 'role': 'assistant'}]