In a marine food chain, the producer level is occupied by:

1. Producers make their own food, so in the sea they must be photosynthetic. 2. Phytoplankton are microscopic photosynthetic organisms drifting in the surface water. 3. They therefore occupy the first trophic level as the producers. 4. Zooplankton eat phytoplankton, so they are the primary consumers at the second level. 5. Placing phytoplankton at the consumer level and zooplankton as producers reverses the chain and was a recorded error. _Source: NECTA ACSEE 2023 Biology 133/2, Question 6: Ecology_