This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enterobecteriaceae, Subject name: Microbiology
Widal test is - 
Select and explain. 
A. Slide flocculation test, B. Immunodiffusion, C. Tube precipitation, D. Tube agglutination
D: Tube agglutination
Answer: D: Tube agglutination 
Explanation: Ans. is 'd' i.e., Tube agglutination Agglutinationo When a particulate antigen is mixed with its antibody in the presence of electrolytes at a suitable temperature and pH, the particles are clumped or agglutinatedo Agglutination is more sensitive than precipitation for the detection of antibodies.Agglutination tests|||||Slide agglutinationTube agglutinationCoombs testPassive agglutination testo Blood grouping and cross - matchingo Widal testo Weil - felix reactiono Paul Bunnell testo Cold agglutination testo Streptococcus MG agglutination testo Anti - Rh antibody test||||| Haemagglutinationo Rose Waaler test for R. A.Latex agglutinationo Detection of: ASO CRP RA factor HOG