Upon exposure to UV radiation, DNA stained with ethidium bromide will show

The separated DNA fragments in agarose gel electrophoresis are visualised using a fluorescent stain, ethidium bromide. The stain, being an intercalating agent, sits between the two strands of a DNA molecule. Upon exposure to UV light, the stain fluoresces as bright, orange-coloured bands.

(2),(3) and (4) DNA stained with ethidium bromide will not show bright red colour, bright blue colour or bright yellow colour when exposed to UV radiation.