Answer:
The correct answer is "flow of energy in an ecosystem".
Explanation:
Traditionally, food chains were established as way to describe the order that organisms are eaten in an ecosystem. However, this concept changed as more information of the ecosystem was gathered trough the years. Nowadays, food chains also describe the flow of energy in an ecosystem, starting by the capture of solar energy by plants that becomes chemical energy stored in the form of biomass that flows from different species along the chain.
