Context: Below is a food web from Shenandoah National Park, a forest ecosystem in Virginia.
A food web models how the matter eaten by organisms moves through an ecosystem. The arrows in a food web represent how matter moves between organisms in an ecosystem.
Which of the following organisms is the decomposer in this food web?
A. beaver
B. gray fox
C. persimmon tree
D. parasol fungus
From the given choices, pick the correct answer and respond by indicating the letter of the correct option.

D