Identify the true statement. a. As the sea floor spreads, the lithosphere rises to fill the space between plates. b. Some magma generated during seafloor spreading erupts from submarine volcanoes. c. New oceanic crust is ultramafic in composition. d. Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called gabbro.

d. Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called gabbro.

Explanation:

beaches, climate, clear water, zinc.

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.