The model shown below represents the transfer of carbon through the atmosphere, soil, and biosphere.




Which of the following describes what is represented by letter Z?

A.
carbon cycling from the geosphere to the atmosphere through the process of fixation

B.
carbon cycling from the atmosphere to the biosphere through the process of respiration

C.
carbon cycling from the biosphere to the atmosphere through the process of decomposition

D.
carbon cycling from the atmosphere to the geosphere through the process of photosynthesis