Which of these organisms is not an omnivore?

A herring

B shrimp

C blue whale

D killer whale

Answer: c Blue whale

Explanation:omnivore is

an animal or person that eats food of both plant and animal origin.

Blue Whale is a carnivorous animal that despite the fact that it doesn't have proper teeth, survives on a diet that is mainly comprised of krill and small crustaceans, along with the occasional small fish.