Carbon dioxide and water vapor are variable gases because

Carbon dioxide and water vapor are variable gases because their amount is not consistent at all parts of the atmosphere.

Surface activities have a significant impact on the abundance of variable gases.This variation arises as a result of the input of surface life activities.They are also not uniformly dispersed due to the characteristics of the gases.Water vapor levels might be low at particular heights.Carbon dioxide and water vapor are variable gases because their amount is not consistent at all parts of the atmosphere.

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Their amount is not consistent at all parts of the atmosphere

Explanation:

Carbon dioxide and water vapor exists as variable gases in the atmosphere because their amount varies from one part to the other.

The abundance of variable gases is influenced strongly by activities from the surface. This variability occurs a result of the contribution from from life activities on the  surface. Also, due to properties of the gases, they are not evenly distributed. At certain altitudes, the amount of water vapor can be low.

The correct answer is c