Given below are six sentences, out of which sentences A and F are in the correct position. Sentences B, C, D and E are in a jumbled order. Select the option that gives the correct order.

A. Carbon is present in the atmosphere, mainly in the form of carbon dioxide (CO2).
B. By process of respiration and decomposition of dead organic matter, it returns back to the atmosphere.
C. The carbon cycle involves a continuous exchange of carbon between the atmosphere and organisms. 
D. Carbon from the atmosphere moves to green plants by the process of photosynthesis, and then to animals.
E. It is usually a short-term cycle. 
F. Some carbon also enters a long-term cycle.