Common stain for fungal hyphae:

Ans is b i.e Gomori Methanamine silver Ref. Chakraboy 2/e 617 "Gomori Methenamine Silver (GMS) and Periodic acid-Schiff (PAS) are the two most common stains used to look for fungi in tissues and in cytology specimens." The GMS stain is more sensitive than the PAS stain as it stains both ble and non-ble fungal elements (which are refractory to other stains) but it stains inflammatory cells (lysosomes) and tissue reticulin too (in addition to fungi.) PAS staining has the slight advantage that the morphology of the tissue adjacent to the fungi can be better visualized, but this can be addressed using a GMS stain and H and E counterstain (which stains only tissue).