15. Not all dead organisms are acted on by decomposers, Instead of being immediately recycled, thed carbon from some organisms is kept in a type of long-term storage, or carbon sink. Using Model 2, answer the questions below about this long-term storage. a. List four materials that contain this stored carbon. b. What is the collective term for these four materials? c. How do humans use the materials in the carbon sink? d. What is the scientific name for the process listed in part \( c \) ? 16. List five examples of combustion in your everyday life.

Many materials contain stored carbon that scientists often classify as fossil fuels. These include coal, oil, natural gas, and peat. When these materials form over millions of years from decaying plant and animal matter, they effectively trap carbon in a long-term storage known as a carbon sink, which plays a crucial role in regulating the Earth's atmospheric carbon levels. Humans utilize these carbon-rich materials in multiple ways that power our daily lives: we burn fossil fuels for electricity, fuel our cars with gasoline, heat our homes using natural gas, produce cement for construction, and manufacture plastics from petrochemicals. This process is commonly known as combustion, where stored carbon is released back into the atmosphere as carbon dioxide, contributing to the carbon cycle.