What type of organism is associated with the breakdown of organic matter?

The correct choice is a decomposer, which plays a crucial role in the ecosystem by breaking down organic matter, such as dead plants and animals, as well as waste products. This process of decomposition not only recycles nutrients back into the soil, making them available for plants to use, but it also helps to keep the environment clean by breaking down and removing decaying material. Decomposers include fungi, bacteria, and some insects, all of which have specialized mechanisms to break down complex organic substances into simpler compounds.

In contrast, predators, parasites, and herbivores have different ecological roles. Predators hunt and consume other organisms for food, parasites live on or in a host organism while deriving nutrients at the host's expense, and herbivores primarily feed on plants. While these types of organisms are important in their own right, their functions do not involve the breakdown of organic matter in the way that decomposers do. Therefore, the role of a decomposer is integral to nutrient cycling and ecosystem health.