**Core Concept**
The question pertains to the identification of a specific stain used for staining fungal elements, which is crucial in the diagnosis of fungal infections. This involves understanding the histopathological characteristics of fungal elements and the staining techniques used to visualize them.

**Why the Correct Answer is Right**
The correct stain used for staining fungal elements is Grocott's Methenamine Silver (GMS) stain. GMS stain is a type of silver nitrate-based stain that selectively stains fungal elements, such as hyphae and yeast cells, against a dark blue-black background. This is achieved through the reduction of silver nitrate to metallic silver, which is then bound to the fungal elements. The resulting stain highlights the fungal elements, making them visible under light microscopy.

**Why Each Wrong Option is Incorrect**
* **Option A:** Hematoxylin and Eosin (H&E) is a general-purpose stain used for routine histopathological examination, but it is not specific for staining fungal elements.
* **Option B:** Periodic Acid-Schiff (PAS) stain is used to detect glycogen and mucin in tissues, but it is not specific for staining fungal elements.
* **Option C:** Alcian Blue stain is used to detect mucin and other acidic polysaccharides in tissues, but it is not specific for staining fungal elements.

**Clinical Pearl / High-Yield Fact**
To remember the specific stains used for staining fungal elements, recall that GMS stain is the preferred method for diagnosing fungal infections, especially in tissue sections.

**Correct Answer:** D. Grocott's Methenamine Silver (GMS) stain.