Carbol-fuchsin contains which components?

• A. basic fuchsin and phenol
• B. acid fuchsin and water
• C. surfactant and dye
• D. methylene blue and solvent

Answer: (A)

Carbol-fuchsin is the primary stain used in acid-fast staining, and it is made by dissolving basic fuchsin dye in phenol. The phenol (carbolic acid) serves as a solvent and helps the dye penetrate the waxy, lipid-rich cell wall of mycobacteria; heating further promotes dye diffusion and retention during decolorization. Because of this, the true composition is basic fuchsin with phenol. The other options don’t fit: acid fuchsin is a different dye, water alone isn’t the solvent here, a surfactant isn’t part of this stain, and methylene blue is used later as a counterstain, not as a constituent of the primary stain.