I think it's the c (<span>.all the gases that surround the Earth)</span>
The red is an oxygen molecule. 1 oxygen and 2 hydrogen =h2o or water!
Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%. Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the atmosphere.
