Here's why:

* Geosphere: This sphere encompasses all the solid, non-living components of the Earth, including rocks, minerals, and soil. Fossil fuels are formed over millions of years from the remains of ancient organisms buried within the Earth's crust.

* Other Spheres:

* Atmosphere: This sphere is composed of the gases that surround the Earth.

* Hydrosphere: This sphere encompasses all the water on Earth, including oceans, lakes, rivers, and groundwater.

* Biosphere: This sphere includes all living organisms on Earth.

While fossil fuels are ultimately derived from the biosphere, they are extracted from the Earth's crust and are considered part of the geosphere.