The Formation of Fossil Fuels
Fossil fuels are formed through a process that takes millions of years. Here is a detailed explanation of how they are formed:
1. Organic Matter Accumulation: The process begins with the accumulation of organic matter, which is primarily derived from plants and microscopic organisms that lived millions of years ago. These organisms include algae, plankton, and other marine life.
2. Burial: Over time, this organic matter gets buried under layers of sediment, such as sand, clay, and rock. The burial process is essential because it provides the necessary conditions for fossil fuel formation.
3. Heat and Pressure: As the layers of sediment continue to accumulate, the organic matter gets exposed to immense heat and pressure. The heat comes from the Earth's core and the pressure is caused by the weight of the overlying sediment.
4. Chemical Changes: The combination of heat and pressure causes chemical changes in the organic matter. This process, known as diagenesis, transforms the organic matter into a waxy substance called kerogen. Kerogen is the precursor to fossil fuels.
5. Cooking Process: As the burial depth and temperature increase, the kerogen undergoes further chemical reactions. This process, known as catagenesis, converts the kerogen into different types of fossil fuels. For example, the catagenesis of kerogen can produce coal, oil, or natural gas depending on the conditions.
6. Migration and Trapping: Once the fossil fuels are formed, they can migrate through porous rocks such as sandstone or limestone. However, they can also get trapped in impermeable rocks, forming reservoirs. These reservoirs are where we typically extract fossil fuels through drilling.
7. Time: It is important to note that the formation of fossil fuels is a slow process that takes millions of years. This is why they are considered non-renewable resources, as they are not replenished on a human timescale.
In conclusion, fossil fuels are formed from the burial and transformation of organic matter over millions of years. The original source of this organic matter is primarily plants and microscopic organisms that lived long ago. The heat and pressure applied to the buried organic matter cause chemical changes, eventually leading to the formation of fossil fuels such as coal, oil, and natural gas.

C is correct