Which of the following best describes the expansion in total railway line kilometers by 1850 in countries that possessed zero kilometers of railroad lines in 1830 ?

cruel, heartless

explanation:

the correct answer is:   the domino theory states that if one country in a region came under the influence of communism, then the surrounding countries would follow in a domino effect.

roosevelt essentially took the opposite approach as hoover in taking on the great depression. herbert hoover thought that america and its economy could naturally recover from the depression in due course, so he adamantly restrained the federal government from intervening on behalf of the people affected. on the other hand, roosevelt dramatically increased employment by expanding the federal government and establishing agencies that would aid in relieving some of the country's worst problems.

i think that the right answer is the aztecs