Answer:
C Volcanic activity releasing carbon into the atmosphere.
Explanation:
The statement that best describes the cycling of carbon between the atmosphere and geosphere among the options is volcanic activity that leads to releasing carbon into the atmosphere.
Volcanic activities has to do with the activity of the geological layer of the earth that leads to the emission of gases, eruption of lava or the combination of the two.
When a volcanic activity leads to the release of carbon related gases such as carbon dioxide into the atmosphere, carbon is being circulated between the geosphere (the earth) and the atmosphere (the air).
Hence, the correct option is C.