Final answer:
In the Earth's geosphere, carbon is primarily found in the form of fossil fuels, which are a non-renewable resource and represent the remnants of ancient organic matter.Option A is the correct answer.
Step-by-step explanation:
Within the Earth's geosphere, you would find fossil fuels as a form of carbon. These are the anaerobically decomposed remains of plants and other organic matter that take millions of years to form.
Found deeper underground, on land and at sea, fossil fuels are a significant carbon reservoir and are considered a non-renewable resource because their rate of use far exceeds their rate of formation. Other forms of carbon, such as that found in soil from organism decomposition or weathered rocks, can also be considered part of the geosphere's carbon content.
Answering the given multiple-choice question, the correct option is (A) Fossils, as they represent carbon that has been stored in the geosphere over extended periods of time.