What best describes the carbon cycle?

The carbon cycle is best described as a process by which carbon is exchanged among various Earth systems. This description encompasses the interconnected systems involved in cycling carbon through the atmosphere, hydrosphere (oceans and rivers), lithosphere (earth's crust), and biosphere (living organisms). Carbon atoms are found in all living organisms and are also stored in fossil fuels, soil, and sedimentary rocks.

Throughout the carbon cycle, carbon undergoes various transformations such as photosynthesis, where plants absorb carbon dioxide from the atmosphere, and respiration, where organisms release carbon back into the atmosphere. Additionally, carbon is also exchanged through processes like combustion and decomposition. This continual movement and transformation highlight the complexity and interconnectedness of carbon cycling across different Earth systems, making option B the most accurate description of the carbon cycle.

The other options do not capture the full scope of the carbon cycle: for instance, one option suggests that the cycle involves only oceanic processes, which is too narrow, as carbon cycling also occurs in terrestrial environments and the atmosphere. Another option focuses exclusively on living organisms, neglecting the role of geological processes and atmospheric interactions. Finally, a suggestion that carbon is irreversibly consumed misses the essence of cycling, where carbon is continuously reused and transformed