Energy in fossil fuels originates from sunlight via photosynthesis

Steps:

• Fossil fuels form from ancient organic matter of plants and animals.
• Energy in this organic matter comes from the food chain, starting with producers.
• Producers, like plants, capture energy through photosynthesis using sunlight.
• Thus, the initial energy source is sunlight absorbed by these producers.

Why D is correct:

• Photosynthesis converts sunlight into chemical energy stored in plant tissues, per the equation 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.

Why the others are wrong:

• A: Geothermal heat does not contribute to organic energy storage in fuels.
• B: Decomposer heat is a byproduct of breakdown, not the initial energy source.
• C: Animal metabolism relies on plant energy, not originating it.

Final answer: D