Final answer:
The correct pairing is Krill - producer in the food chain
Step-by-step explanation:
The correct pairing of an organism with its role in the food chain is Krill - producer. In a food chain, the producer is the organism that converts sunlight energy into food through photosynthesis. Phytoplankton are microscopic plants that float on the water's surface, making them the producers in this food chain. Krill, on the other hand, are small crustaceans that consume phytoplankton, making them the primary consumers.
Learn more about food chain