The rockskipper is the organisms to be eaten by an omnivore in the food web, option A.
Why is it the rockskipper?
This is because the rockskipper is a primary consumer, meaning it eats only plants. Omnivores, on the other hand, eat both plants and animals. Therefore, the rockskipper is a potential food source for any of the omnivores in the food web, such as the trout, the sea otter, or the raccoon.
The food web shows that the rockskipper is preyed upon by the seagull, which is an omnivore. Seagulls eat a variety of food items, including fish, invertebrates, and other birds.