Answer:
The correct answer is (a) safranin.
Step-by-step explanation:
Safranin is the dye used as the counterstain (secondary stain) in the Gram stain procedure.
During the Gram stain procedure, crystal violet is used as the primary stain, staining all purple bacterial cells. Then, iodine is used as a mordant to fix the stain in the cell wall, making it difficult to remove. In the next step, the decolorizing agent (usually ethanol or acetone) is applied, removing the crystal violet from Gram-negative bacteria but not Gram-positive ones. Finally, safranin is used as the counterstain, which stains the Gram-negative bacteria pink, allowing them to be differentiated from the Gram-positive bacteria that appear purple.
The correct answer is (a) safranin.