Ans: B (RNA) Ref: Ananthnarayan, Paniker CJ, Textbook of Microbiology, 8th edition, London: John Wiley and Sons, 2009, pg: 69Explanation:Southern Blotting:o Highly sensitive technique for identifying DNA fragments by DNA- DNA hybridization.o This technique has very wide applications in DNA analysis.Northern Blotting:o Used for the analysis of RNA.o Procedure is analogous to southern blotting, hence the name northern blotting.o Here the RNA mixture is separated by gel electrophoresis, blotted and identified using labelled DNA or RNA probes.Western Blotting:o A similar technique for the identification of proteins {antigens) is called immunoblotting {or, in conformity with other blotting techniques, western blotting).o Here the protein antigen mixture is separated by SDS-PAGE (sodium dodecylsulfate-polyacrylamide gel electrophoresis),blotted on to nitrocellulose strips and identified by radiolabeled or enzyme-labeled antibodies as probes.o E.g. Western blot test for detection of antibodies directed against different antigens of HIV.