What are fossil fuels primarily composed of?

Fossil fuels are primarily composed of hydrogen and carbon, making option B the correct choice. This composition is crucial because the carbon content is what allows fossil fuels to store energy, while hydrogen is responsible for producing energy when these fuels are burned.

When fossil fuels such as coal, oil, or natural gas are combusted for energy, the chemical reaction primarily involves the carbon in these fuels reacting with oxygen from the air to produce carbon dioxide, water, and energy. The high energy density of fossil fuels is largely a result of their carbon and hydrogen structure, which makes them effective sources of energy for transportation, electricity generation, and heating.

While other elements may be present in fossil fuels, such as sulfur in coal or nitrogen compounds in petroleum, the fundamental makeup that defines fossil fuels as a category is their significant hydrogen and carbon content.