**Core Concept**
The question is testing the knowledge of fungal stains used in histopathological examination of tissue biopsy sections. Fungal stains are essential in identifying fungal infections, which are an important cause of morbidity and mortality in immunocompromised individuals.

**Why the Correct Answer is Right**
Methenamine silver (also known as Grocott's methenamine silver) is a widely used fungal stain that highlights the fungal elements in tissue sections. It is a silver-based stain that is specific for fungal cell walls and is commonly used in routine histopathology labs. The mechanism of action involves the deposition of silver ions on the fungal cell walls, making them visible under a microscope.

**Why Each Wrong Option is Incorrect**
**Option A:** H&E (Hematoxylin and Eosin) is a routine histopathology stain used for general tissue examination, but it is not specific for fungal elements. It stains the tissue background and may not highlight the fungal cells.

**Option B:** Periodic Acid-Schiff (PAS) is a stain used to detect glycogen, mucins, and other carbohydrate-containing molecules in tissue sections. While it can highlight some fungal elements, it is not as specific as methenamine silver for fungal staining.

**Option C:** Alcian blue is a stain used to detect mucins and other acidic glycoproteins in tissue sections. It is not used for fungal staining and may not highlight the fungal elements.

**Clinical Pearl / High-Yield Fact**
When examining tissue biopsy sections for fungal infections, it is essential to use a specific fungal stain like methenamine silver to highlight the fungal elements. This can help in diagnosing fungal infections, which are often challenging to diagnose based on clinical symptoms alone.

**Correct Answer:** C.