Oil shale
It was discovered in the region in the 1970s. it spurred economic growth in the neighboring areas of Colorado. however major a discovery it was, the industry declined leading to copper, silver and gold being the most important mineral resource in the Rockies mountain.
I could be wrong but I think its 2
<span>C) movement from rural areas to urban areas--the late 1800s is a period of urbanization connected to industrialization in the US
The Gilded Age is a period of industrialization which brought large numbers of people from rural areas to the cities to obtain work. More technology made farming easier and less people were needed to farm therefore cities offered a better way of life. </span>
B. The Cold War
The Cold War was pretty much who had the best weapons, technology or advances in technology, science, etc.
Answer:
I'm not able to give a definite answer, but I am able to narrow the answer choices down to where it's either A or D.
