The correct statement regarding the role of fossil fuels in the carbon cycle is: "Fossil fuels are rich in carbon and burning them releases carbon into the atmosphere."
When fossil fuels (such as coal, oil, and natural gas) are burned for energy, the carbon that was stored in these fuels is released as carbon dioxide (CO2) into the atmosphere. This process contributes to the greenhouse effect and climate change by increasing the concentration of carbon dioxide in the atmosphere, which is a significant greenhouse gas. Overall, fossil fuels are integral parts of the carbon cycle, acting as a reservoir of carbon that, when combusted, transfers carbon from the lithosphere into the atmosphere.