Fossil fuels form from ancient organic matter buried and transformed by heat and pressure; main types are coal, oil, and natural gas.

• A. They form from volcanic rocks.
• B. They form from ancient organic matter buried and transformed by heat and pressure; main types are coal, oil, and natural gas.
• C. They form from solar energy stored in living matter.
• D. They are produced by photosynthesis.

Answer: (B)

The main idea here is that fossil fuels come from ancient organic matter that’s buried under sediments and slowly transformed by heat and pressure over long timescales. This maturation turns plant- and microbe-rich material into coal through coalification, and into liquid and gaseous hydrocarbons as kerogen-rich material is heated to higher temperatures, producing oil and natural gas. Because of these distinct pathways, coal, oil, and natural gas are the primary products we call fossil fuels.

That’s why the statement is the best description: it captures both the formation process (burial, heat, and pressure) and the resulting main types (coal, oil, natural gas). The other options misstate how fossil fuels form—volcanic rocks are igneous, not the source of hydrocarbons; while solar energy and photosynthesis are part of how organic matter originally arrives on Earth, they don’t describe the deep-burial transformation that creates fossil fuels.