Context: Below is a food web from an ocean ecosystem. The ecosystem is in Monterey Bay, off the coast of California.
A food web is a model that shows how the matter eaten by living things moves through an ecosystem. The arrows show how matter moves through the food web.
Based on the arrows, which of the following living things is a producer?
A. phytoplankton
B. zooplankton
From the given choices, choose the correct answer and respond with the letter of that choice.

A