Final answer:
Carbon matter is primarily found in the Earth's crust and oceans. Plants consume carbon dioxide and release it back into the atmosphere through respiration and decay.
Step-by-step explanation:
The most carbon matter on Earth is found in the crust and oceans. In the crust, carbon is stored as calcium and magnesium carbonate in sedimentary rocks. The oceans contain a large reservoir of carbon, primarily as the bicarbonate ion (HCO3). Additionally, green plants consume carbon dioxide during photosynthesis, and it is released back into the atmosphere through respiration and decay.