A stain applied after the main tissue component is highlighted to provide contrast so the main component stands out better.

• A. Counterstain
• B. Accentuator
• C. Differentiation
• D. Dehydration

Answer: (A)

The idea here is using a counterstain to create contrast after the main structure has been highlighted. A counterstain is a second stain applied after the primary stain so it colors different components in a distinct color, making the primary structure stand out more clearly. For example, in hematoxylin and eosin staining, hematoxylin highlights the nuclei, while eosin—the counterstain—colors the cytoplasm and extracellular matrix in pink, providing clear contrast that helps you see tissue architecture.

The other terms don’t describe this step. Accentuator isn’t a standard staining term for adding contrast after the main stain. Differentiation is more about distinguishing between colors by removing excess stain or reducing color intensity, not about adding a contrasting color. Dehydration is a preparatory step to prepare tissue for mounting, not a staining step.

So, the best answer is the counterstain, because it’s specifically defined as the stain applied after the primary component to provide contrasting color and enhance visibility.