Climate change is expected to affect tropical and temperate species differently. Select the statement that best describes which type of species is more at risk, and why.

A. Tropical species, because they have a narrow performance curve with a small thermal safety margin.
B. Tropical species, because they have a broad performance curve with a large thermal safety margin.
C. Temperate species, because they have a narrow performance curve with a small thermal safety margin.
D. Temperate species, because they have a braod performance curve with a large thermal safety margin.

answer: s     se x

explanation:

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.