Final answer:
Ecosystems are composed of producers (plants and algae), consumers (herbivores, carnivores, omnivores), and decomposers (fungi, bacteria). Together, these components contribute to the flow of energy and recycling of nutrients in nature. Humans fit into this framework as omnivores and tertiary consumers.
Step-by-step explanation:
The correct components of an ecosystem are producers, consumers, and decomposers (Option A). Producers, such as plants and algae, are organisms that make their own food through photosynthesis and form the base of food webs. Herbivores that eat producers are classified as primary consumers. Predatory animals that eat primary consumers are secondary consumers, while those that eat secondary consumers are tertiary consumers. The decomposers, like fungi and bacteria, break down dead organisms and recycle nutrients back into the ecosystem.
Humans are classified as omnivores because they consume both plants (producers) and animals (consumers). Humans can also be considered tertiary consumers due to their place in the food chain where they consume primary and secondary consumers. In detrital food webs, decomposers act as primary producers by recycling nutrients, while in grazing food webs, the primary producers are often photosynthetic organisms. It's important to note that the terms autotrophs and heterotrophs are broader categories; autotrophs like plants produce their own food, while heterotrophs, including all animals, fungi, and many bacteria and protists, obtain their food by consuming other organisms or organic matter.