In Ecosystems, Why Is the Term Cycling Used to Describe

In ecosystems, why is the term cycling used to describe the transfer of chemical elements, whereas the term flow is used for energy exchange?

A) Chemical elements are repeatedly used, but energy flows through and out of ecosystems.
B) Photosynthesis and feeding relationships result in transforming chemical elements, but not energy.
C) Chemical elements are transferred into ecosystems from other ecosystems, but energy is only transferred within a single ecosystem.
D) In an ecosystem, the total amount of chemical elements does not change, whereas the total amount of energy can change.