Which of the following is a primary producer in an ecosystem?

In an ecosystem, primary producers are organisms that can produce their own food through the process of photosynthesis or chemosynthesis. Plants are the most common example of primary producers, as they convert sunlight into energy through photosynthesis, using carbon dioxide and water. This energy is then passed on to other organisms in the food chain, such as herbivores, which eat plants, and subsequently, carnivores, which may eat those herbivores.

While herbivores, carnivores, and decomposers play important roles in the ecosystem, they do not produce their own energy. Herbivores consume plants (the primary producers), carnivores consume herbivores, and decomposers break down dead organic matter, recycling nutrients back into the soil but not generating their own energy. Thus, plants are correctly identified as primary producers because they form the foundation of energy in a typical food web.