What structure represents the main body of a fungus?

The mycelium is the main body of a fungus, consisting of a network of filaments known as hyphae. Mycelium serves as the vegetative part of the fungus and is responsible for nutrient absorption and growth. It spreads throughout the substrate, allowing the fungus to decompose and absorb organic material, which is vital for its sustenance and reproduction.

Hyphae are the individual filamentous structures that make up the mycelium, but they do not represent the full body of the fungus on their own. A sporangium is a structure that produces and contains spores, while a basidium is a microscopic structure found in certain fungi involved in spore production, specifically in the class of fungi known as Basidiomycetes. These structures play roles in reproduction but do not form the main body of the fungus. Thus, the mycelium is correctly identified as the primary growth structure of a fungus, encompassing the collective network of hyphae.