Dye used for direct immunofluorescence ?

Ans. is 'c' i.e., Rhodamine Fluorescent microscopy helps to provide rapid diagnosis. When ceain dyes are exposed to ultraviolet light, they absorb energy and emit visible light, i.e. they fluoresce. Tissue or organisms stained with such a dye and examined with U.V. light in a specially adapted microscope are seen as fluorescent objects. Antibody can also be labelled by conjugation with a fluorescent dye and this fluorescent antibody is allowed to react with homologous antigen exposed at a cell surface - Direct immunofluorescence test.