What is the next phase of the carbon cycle for the carbon source labeled b? a. condensation b. transpiration c. photosynthesis d. decomposition

D. Decomposition

Decomposition is the process that leads organic compounds to be broken down into simpler molecules until Carbon is in a more stable state. That's why the B label is next to the soil organic matter. It is that matter that will be decomposed and, therefore, is a Carbon source. This decomposition is done by organisms called decomposers. 

Organism, organ system, organs, tissue, cells