Answer:
C. To recycle molecular building blocks
Explanation:
In the shown food web, almost all organisms are the food source for the fungus. They feed on dead organic matter. Fungi breakdown dead organic matter into basic nutrients such as derivatives of C, N, O, P, K, etc. These nutrients then act as building blocks of macromolecules amino acids, carbohydrates, fats, nucleic acids required for the biogeochemical functioning of the food web.
PS: Fungi work as primary decomposers in an ecosystem like bacteria.
