Which of the following statements is most accurate? A--A finite amount of carbon exists on Earth, and it moves through living and nonliving materials through the carbon cycle.

B--The amount of carbon on Earth cycles, gradually increasing as it moves up the food chain, and decreasing until the next phase of the cycle.

C--Carbon flows through the food chain as animals eat it, then decomposes and is permanently removed from the system when the food chain is complete.

D--Carbon enters Earth's atmosphere when animals exhale, then moves into space where its amount steadily increases, and finally moves back into Earth's atmosphere to be used again