Final answer:
Decomposers are associated with detrital food webs and are considered detritivores, consuming decomposed organic material from all trophic levels.
Step-by-step explanation:
Decomposers are organisms that break down dead or decaying organisms, and in doing so, carry out the natural process of decomposition. They play a crucial role in nutrient cycling and are an essential component of the ecosystem, helping to recycle nutrients. Decomposers are associated with detrital food webs, which is a type of food web in which the primary consumers consist of decomposers; these detritivores are often associated with grazing food webs within the same ecosystem.
Among the options provided, d) Detritivores is the class of the food web with which decomposers are associated. Decomposers and detritivores directly obtain nutrients by consuming decomposing organic materials from all trophic levels, unlike tertiary consumers which rely on consuming primary and secondary consumers.