What do larvae of most Gnat species typically do?

The correct answer reflects the ecological habits of gnat larvae, which are commonly found in environments rich in organic material. Most gnat species, particularly those in the family Sciaridae (fungus gnats), have larvae that thrive in damp soil or water where decaying organic matter is abundant. This habitat supports their feeding needs, as they typically consume a variety of organic substances, including decomposing plant material, fungi, and microorganisms.

The other options describe habitats or behaviors that are not representative of gnat larvae. For instance, living exclusively in trees is not accurate, as gnat larvae are generally found in moist soil or water rather than in arboreal locations. Additionally, while some plant roots may be consumed, the diet of gnat larvae is much broader and includes various organic matter rather than being limited strictly to plant roots. Finally, the notion of residing in clean, dry areas contradicts their natural habitat preferences since gnat larvae require moisture and decomposing materials for sustenance. This further underscores why the typical behavior of gnat larvae aligns with the feeding on organic matter in damp environments.