The correct answer is option 2: Biosphere. The biosphere refers to the regions of the Earth where living organisms exist. It includes all parts of the planet where life can be found, such as the air, land, and water. The biosphere is where ecosystems are formed and where different species interact with each other and their environment.

Option 1, Biomass, refers to the total mass of living organisms within a given area or ecosystem. It does not refer specifically to the space retaining life.

Option 3, Lithosphere, refers to the rigid outer part of the Earth, including the crust and upper mantle. While some organisms may exist in the lithosphere, it does not encompass the entire space retaining life.

Option 4, Hydrosphere, refers to all the water on Earth, including oceans, lakes, rivers, and groundwater. While aquatic organisms exist in the hydrosphere, it does not encompass the entire space retaining life.

In conclusion, the biosphere is the correct term for the space retaining life in any form.