Which of the following is a basic dye?

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Basic dyes are salts of colored organic bases containing amino groups ( -NH₂ , -NHR , -NR₂ ). In aqueous solution, they form colored cations. Aniline yellow (p-aminoazobenzene) contains an amino group, which makes it basic in nature. It gets protonated in an acidic medium to form a colored cation, hence it is classified as a basic dye. Alizarin is a mordant dye. Congo red is a direct dye (and an acidic dye due to the presence of sulfonic acid groups). Indigo is a vat dye. Answer: Aniline yellow