This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Microbiology
Dye used for direct immunofluorescence - 
Select and explain. 
A. India ink, B. Nigrosin, C. Rhodamine, D. Basic fuschin
C: Rhodamine
Answer: C: Rhodamine 
Explanation: Ans. is 'c' i.e., Rhodamine o Fluorescent microscopy helps to provide rapid diagnosis. o When certain dyes are exposed to ultraviolet light, they absorb energy and emit visible light, i.e. they fluoresce, o Tissue or organisms stained with such a dye and examined with U.V. light in a specially adapted microscope are seen as fluorescent objects. o The antibody can also be labeled 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, o The fluorescence dye used commonly are - # Auramine # Lissamine # Rhodamine # Fluoresceine isothiocyanate