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.
In this food web, which organism contains matter that eventually moves to the earthworm?
A. barren-ground caribou
B. Arctic fox
Determine the correct option from the provided choices and reply with its corresponding letter.

B