Final answer:
The best description for a clownfish is 'C) Omnivorous fish', as they feed on both plant and animal material and live symbiotically with sea anemones in oceanic coral reefs.
Step-by-step explanation:
The question asks which of the following best describes a clownfish. The correct answer is C) Omnivorous fish. A clownfish, like Amphiprion ocellaris pictured in coral reefs, is a type of fish that feeds on both plant and animal material, making it omnivorous. Clownfish are not mammals, reptiles, or birds, and they do not feed exclusively on plants, meat, or insects. Also, clownfish live in ocean environments, often in symbiosis with sea anemones. Therefore, they are neither herbivorous mammals, carnivorous reptiles, nor insectivorous birds, but they are indeed swimming, omnivorous creatures within oceanic coral reefs.