Why is air never completely dry?
A) Water vapor makes up as much as 4 of the atmosphere
B) Clouds and fog are actually liquid droplets of water
C) Water's very presence in the atmosphere accounts for dew, rain, and snow
D) All of these choices
Question 2
Ocean basins have opened and closed over great spans of time during Earth's history. This process of opening and closing is called a _____.
A) Wilson cycle
B) divergent-convergent cycle
C) convection current
D) uplift-subduction cycle