In this model food web, one organism uses sunlight, water and carbon dioxide to build its own food, and several animals eat it. What role does that organism have?

Explanation

An organism that uses sunlight, water and carbon dioxide to build its own food supplies energy to the web instead of taking energy out of it, which is the role at the base of every food chain here. The plant-eating role one step higher does not fit, because an animal at that level has to eat something that already made the food, while this organism makes its own.