Answer:
its "C"
Step-by-step explanation:
On our planet we can survive thanks to a layer of different composition of gases that surrounds the whole Earth. This layer remains on Earth thanks to gravity. It is the earth's atmosphere, and it is difficult to determine exactly its thickness, since the gases that make it up become less dense with height, until they practically disappear a few hundred kilometers from the surface.
The atmosphere fulfills various functions for life on the planet and without it we would not be able to have life as we know it.