Context: Below is a food web from a tundra ecosystem in Nunavut, a territory in Northern Canada.
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 these organisms contains matter that was once part of the bilberry?
A. bear sedge
B. barren-ground caribou
C. mushroom
From the given choices, select the correct answer and reply with the letter of the chosen option.

C