How did the rock of the Great Plains and Rocky Mountains form? They gave me two sentences and I have to eliminate one

Formation of Plains

As mountains and hills erode, gravity combined with water and ice carry the sediments downhill, depositing layer after layer to form plains. Rivers form plains through related processes. As rivers erode rock and soil, they smooth and flatten the land they pass through.

Source: https://sciencing.com/great-plains-were-formed-5260966.html

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d