What does the biosphere encompass?

The biosphere encompasses all regions of Earth where living organisms exist. This includes not just the land, but also the oceans and the atmosphere where life can be found. The biosphere is essentially a global sum of all ecosystems and represents the zones of life on Earth, from the deepest ocean floors to high in the atmosphere. By understanding the biosphere in this way, it allows us to appreciate the interconnectedness of all living beings and their environments, highlighting the importance of various ecosystems and their contributions to the health of the planet.

The other options refer to specific aspects of Earth's environment: while liquid water is indeed crucial for life, and solid layers of the Earth and its atmosphere are integral parts of our planet, they do not encompass the full range of biological habitats that define the biosphere.