Context: Read the passage. Then answer the question below.

In a tide pool in California, California mussels live up high on the rocks. They are only submerged during high tide, when the water level is the highest.
Giant green anemones and ochre sea stars live lower in the tide pool. They are submerged during high tide but exposed to air during low tide, when most water drains out of the tide pool.
Species such as red octopuses and fluffy sculpin fish must stay underwater at all times. So, they swim in parts of the tide pool that are underwater even at low tide.
Figure: a tide pool containing mussels, sea stars, and anemones.
Which of the following best describes an ecosystem in a California tide pool?
A. a school of fluffy sculpins
B. the giant green anemones, the ochre sea stars, and the red octopuses
C. the rocks, the salt water, and the California mussels
Answer with the option's letter from the given choices directly.

C