The correct answer is D. Steel
The answer is B. folding, uplift, and erosion. certain mountains are created from the folding of the upper layers of earth's crust. valleys on the other hand are made from the erosion of land or soil. tectonic uplift of the earths crust is also responsible for creating mountains.
Answer:
A, They mapped the land and reached the Pacific Ocean, helping the US set claim.
Add-on:
I hope this helped at all. I'm sorry if its incorrect.
