Hint: An ecosystem could be any functional unit of nature in which both biotic and abiotic components are present. The abiotic components include air, soil, and water, while the biotic components include producers, consumers, and decomposers.
The biotic and abiotic components interact in the ecosystem and lead to production, decomposition, and flow of energy and nutrients. In primary production, the solar energy is captured and utilized by plants and some other organisms to produce food. The food is then consumed by the consumers (secondary production) and the energy is passed through the food chain. The dead and decay are then decomposed and complex organic matter is converted into simpler inorganic nutrients, carbon dioxide, and water.
The food chain in which the microorganisms break down the compounds synthesized by producers that are rich in energy is the Detritus food chain (DFC). The DFC starts with the dead organic matter and is composed of decomposers including fungi and bacteria. These decomposers are heterotrophic organisms. They degrade the dead organic matter known as detritus and then absorb the simple inorganic material produced.
Hence, the correct answer is option (C).
Detritus food chains sometimes get linked to the grazing food chain as the organisms of DFC could become the prey to grazing food chain animals at some level. This natural connection between different food chains is known as the food web.
Note: The organisms that are utilized in the process of decomposition are also known as saprotrophs, in which ‘sapro’ means to decompose. These saprotrophs secrete digestive enzymes that decompose the dead and decay materials.