The Monroe doctrine was the reaction and effect of the European powers plan to help Spain create or retake colonies in America. the doctrine, enacted in 1823,pointed out that the USA would intervene to protect the peace and freedom of independent states in the region of America.
Answer: here.
Explanation:
The correct is C) the transcontinental railroad
It made it harder for immigrants to become citizens and made it so the president could imprison non citizens.
The progressive era brought significant reforms to American industrial capitalism and to the American political system, through participation and activism by ordinary Americans. The progressives had organized to improve the working and living conditions for poor people, only really to address the glaring social and environmental problems, as well as expand opportunies for democratic involvement in the political system.
