The image’s technique is described as regressive. Which term matches this description?

• A. regressive
• B. progressive
• C. additive
• D. differential

Answer: (A)

Regressive staining is a technique where you deliberately overstain the tissue and then use a decolorizing step to selectively remove stain from components with weaker affinity. This overcoloring followed by differentiation yields crisper contrast, because structures that bind the dye strongly (like nuclei) stay intensely colored while others lose color. That’s why the description fits: the image shows a process built on overstaining and then partial color removal to sharpen detail. If it were progressive, you’d stain to the desired end color without a decolorization step, resulting in less selective contrast. Additive staining would just add colors without removing any, and differential staining is a broader concept about using multiple stains to distinguish components, but it isn’t defining the regressive approach itself.