Which sequence correctly represents the Mayer's mucicarmine staining procedure?

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Mayer's mucicarmine staining is used to highlight acidic mucins by staining them a bright red, while keeping nuclei and surrounding tissue clearly separated for contrast. The proper sequence starts with a nuclear stain, specifically Weigert's hematoxylin, to color the nuclei blue-black. Next, the mucicarmine stain binds to the mucopolysaccharides in mucin, producing a red color without disturbing the already stained nuclei. Finally, a counterstain such as metanil yellow is applied to give a yellow background and additional contrast to the tissue, helping the red mucin stand out more distinctly. If mucicarmine were applied before the nuclear stain, or if the counterstain were used too early, the nuclear or background contrast would be compromised and the mucin might not be as clearly distinguished. Thus, staining nuclei first, then mucicarmine, and finally applying the counterstain yields the clearest differentiation, which is why this sequence is correct.