When Khrushchev demanded that US troops leave West Berlin, Kennedy responded by calling up additional troops.
building the Berlin Wall.
withdrawing troops from the city.
launching the Bay of Pigs invasion.

answer; i believe its (cpr);

monopolies  came to the united states with the colonial administration. the large-scale public works needed to make the new world hospitable to old world immigrants required large companies to carry them out. these companies were granted exclusive contracts for these works by the colonial administrators. even after the american revolution, many of these colonial holdovers still functioned due to the contracts and land

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the answer should be a. the sui empire, the tang empire extended from korea in the west to manchuria in the east.

the answer i chose to believe is 'harmony'