Which organisms are classified as nematodes?

Nematodes, commonly referred to as roundworms, are indeed classified as small roundworms that primarily inhabit soil and various aquatic environments. They are a diverse group of organisms that can range in size and are characterized by their elongated, cylindrical body shape. Nematodes play significant roles in ecosystems, including nutrient cycling, soil health, and as both beneficial and harmful organisms in agriculture.

The other options represent entirely different groups of organisms. For instance, large root-eating insects would refer to a variety of insect species that damage plant roots rather than nematodes. Fungi decompose organic matter, contributing to soil fertility but are distinct from nematodes in their biological classification. Bacteria, while they can infect plants and play various roles in ecosystems, are microorganisms entirely different from nematodes. Thus, the classification of nematodes specifically aligns with small roundworms found in soil, highlighting their unique characteristics and ecological functions.