Which of the following rocks is used for fuel?

The rock that is used for fuel is called lignite. Lignite is a type of sedimentary rock that is formed from compressed peat. It is brown in color and has a soft texture, which makes it easy to mine. Lignite is used as a fuel because it has a high moisture content and low carbon content, which means it burns easily and produces a lot of heat. Lignite is mainly used to generate electricity in power plants, and it is also used as a fuel in some homes for heating and cooking. So, if you are looking for a rock that is used for fuel, the answer is lignite.