In what direction does energy flow through an ecosystem?

Energy flow through an ecosystem starts with primary producers, such as plants and phytoplankton, which convert sunlight into chemical energy through photosynthesis. This energy is then transferred through various levels of consumers in the food chain, where herbivores consume the producers, and then these herbivores are eaten by carnivores.

This directional flow—where energy moves from producers to primary consumers, and then to secondary and tertiary consumers—is what makes option C the correct choice. Each level of the food chain, or trophic level, relies on the energy provided by the level below it, demonstrating a one-way flow of energy rather than a circular one. Understanding this path is crucial in ecosystems, as it highlights the dependency of various organisms on those that produce energy directly from sunlight.