Which is used to determine earthquake risk a. changes in the color of rocks near faults b. hydrogen gas emissions near fractures c. the height of ocean waves d. strain in rocks near faults

The option (b) ''Hydrogen gas emissions near fractures'' is the correct option.

Explanation:

Hydrogen gas is highly mobile and insoluble in the earth's water. It causes the mechanical changes in the crustal rocks due to its high mobility nature.  

When it flows into the water, it reacts with water and forms hydrogen peroxide. The outflow of the charges causes electric current in the earth's crust. If it will continue emitting charges then it will cause EM pulses which will lead to the earthquake

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.