Answer:
Option: They wanted to seek silver and gold there.
Explanation:
Americans first travel across the Great Plains to get gold and silver in the 1800s. After the Civil War, a vast amount of people from the east began to move in the West in search of gold. The first wave of settlers to the West were miners. The great plains region consists of Texas, Colorado, Kansas, Nebraska, and Oklahoma.
The correct answer should be the industrial revolution. People started developing technologies that helped prevent diseases and this caused many more children to survive and many more people to live longer. The advances made in medicine are the key to rapid population growth, as well as era's like the world war 2 era after which came the baby boom generation where the population growth was at an all time high.