An ocean food web is shown.

In an ocean food web, the organism that has the most available energy is typically the primary producer, which is usually a plant or algae. In this case, the kelp would have the most available energy, as it captures energy from the sun through photosynthesis and serves as the base of the food web. The energy decreases as it moves up the food chain to herbivores like sea urchins, and then to higher-level consumers like sea otters and elephant seals. Therefore, the correct answer is kelp.