Context: Below is a food web from an ocean ecosystem in Monterey Bay, off the coast of California.
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 sea cucumber?
A. black rockfish
B. sea otter
Answer with the option's letter from the given choices directly.

B