Which of the following statements about mining is true?
a. mining has no long-term effects on the earth.
b. mining is unimportant to the economy.
c. mining has no ecological impact.
d. mining allows useful minerals to be extracted from the earth.

The following statements about mining is true: Mining allows useful minerals to be extracted from the Earth. Correct D

Mining has a large impact on the environment because minerals are contained within the Earth. The long term effects of mining include acid drainage , erosion and dust emissions.

the first phase of the government’s plan for settlement was building the transcontinental railroad. the railroad provided a way to bring settlers and manufactured goods west and ship their agricultural and mining produce east. the transcontinental railroad was an essential artery for rapid development of the frontier.

the second phase of the government’s plan was a liberal land distribution policy that made it possible for many people to homestead. with these two key elements—transportation and cheap land—the government rapidly achieved its goal of persuading people to move west, settle on farms, and push back the frontier.