What is the composition of dry air primarily made up of?

The composition of dry air is primarily made up of nitrogen, oxygen, and argon. This means that the correct answer is the first choice, which highlights the dominant gases present in Earth's atmosphere.

To understand why this composition is significant, nitrogen constitutes about 78% of the atmosphere, making it the most abundant gas. Oxygen, required for respiration by living organisms, accounts for about 21%, while argon, an inert gas, makes up about 0.93%.

The other options include combinations of gases and elements that do not accurately represent the primary constituents of dry air. For instance, carbon dioxide and water vapor are present in the atmosphere, but they are only trace gases compared to nitrogen and oxygen. Ozone is also a minor component and primarily found in specific layers of the atmosphere, not representing the bulk of dry air composition. Therefore, the selection that highlights nitrogen, oxygen, and argon correctly reflects the true makeup of the air we breathe.