The correct answer is - a. geosphere.
The geosphere is the sphere that includes in it the core, mantle, and crust, thus the harder, more solid parts, liquid metals, of the interior and surface of out planet. It is strictly orientated and composed by not organic matter. The geosphere is one of the few spheres of our planet, and it is one of the most interesting for studying of the geography, mainly the geology and geomorphology disciplines of it.