Final answer:
The correct answer is B. KOH, which is used in wet mount preparations to dissolve cellular material to aid in the microscopic examination of fungi and bacterial spores.
Step-by-step explanation:
The preparation that destroys bacteria and epithelial cells to allow microscopic examination of fungi and bacterial spores is B. KOH. Potassium hydroxide (KOH) is commonly used in wet mount preparations to dissolve keratin in hair, nails, and skin cells, enhancing the visibility of hyphae and fungal spores under a microscope. This preparation is particularly useful when dealing with fungal infections, as the high pH of KOH disrupts the cellular structure of bacterial and human cells, but not of the fungi, thereby allowing for more accurate observation and diagnosis.
Agar, such as Sabouraud dextrose CC, might be utilized to grow cultures of the specimen. Gram stain is another technique used for distinguishing and identifying bacterial species, typically by the color they show after the staining procedure. However, Gram stain is not the correct answer here as it does not specifically dissolve cellular tissue for the purpose of visualizing fungi and spores.