The choices for this question are:
-is biologically magnified in ... are recycled in
-is dissipated in ... flow through
-flows through ... are recycled in
-is continuously supplied to ... are continuously removed from
-is recycled in ... flow through
On a global scale, energy flows through ecosystems whereas chemical elements are recycle in ecosystems. So the answer is the third option.
Energy flows through the ecosystem. Most energy comes from sunlight and it is transformed into chemical energy by autotrophs. When they are consumed by heterotrophs the energy is passed on, until it dissipates as heat.
Chemical elements like carbon and nitrogen, on the other hand, are cycled between biotic and abiotic factors in an ecosystem. This is not possible for energy. These chemical elements come from abiotic factors like the air, light and soil. They are incorporated in the biomass of the photosynthetic organisms and are consumed by other organisms. They are changed back into their inorganic form when the organism dies and are broken down by decomposers and the cycle goes on. So they are constantly being recycled.
In summary, energy needs a continuous source to be able to maintain and sustain the energy flow in the ecosystem. Chemical elements, on the other hand, are just recycled through processes between abiotic factors and biotic factors.