Earth's tectonic activity is a significant factor that made life on earth possible because the movement of earth's crustal plates affects a. volcanic activity and the atmosphere b. mountain ranges c. water resources d. solar energy

The correct answer is - A. volcanic activity and the atmosphere.

The movement of the crustal plates is extremely important for the life on our planet, and that is because it cause the volcanic and post volcanic activities, and contributes to the composition of gases in the lower atmosphere. The volcanoes release large amounts of lava, pyroclastic material, ash, and gases. The first two are very important for the formation of rocks, which later on in time become soil, while the ash is one of the best natural fertilizers of the soil. The gasses, mostly the carbon dioxide, are released in huge amounts, and that is very important for the sustainability of the Green House effect which is crucial in the sense that it is the reason why the planet is warm enough so that life on it can flourish.

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.