Answer:
The correct word to fill the blank is "hyphae"
Explanation:
Multicellular fungi are made of a network of long, thin filaments known as hyphae. Most of the fungi are multicellular. Multicellular fungal bodies are composed of a network of hyphae, Hyphae or hypha (singular) is composed of, end to end connected tubular cells called septa.
Example: Molds and Mushrooms.