Final answer:
The substance that couldn't be a component of fossil fuel is H-.
Step-by-step explanation:
From the given options, the substance that couldn't be a component of fossil fuel is H-. Fossil fuels, such as coal, oil, and natural gas, are mainly composed of carbon and hydrogen atoms. Oxygen atoms can also be present in fossil fuels, but they are typically found as part of other elements such as carbon dioxide. The H- ion is a negatively charged hydrogen ion, and it wouldn't be found as an individual component in fossil fuels.
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