Since a decomposer feeds on dead organisms, the scenario that describes a fungi as a decomposer is fungus growing on dead leaves. The correct answer is B.
Fungi is a class of saprophytic organisms, which means they do not produce their own food but obtain their food by degrading dead and decaying plants and animals. They are valuable decomposers, as they break down decaying matter into simpler substances, that is utilized by the plants. The fungus growing on the dead leaves is an example of the fact that fungi as a decomposers because it will obtain nourishment by degrading the leaf to form it's own fungal colony.
