Read the excerpt from "a quilt of a country."

what is the point of this splintered whole? what is the point of a nation in which arab cabbies chauffeur jewish passengers through the streets of new york—and in which jewish cabbies chauffeur arab passengers, too, and yet speak in theory of hatred, one for the other? what is the point of a nation in which one part seems to be always on the verge of fisticuffs with another, blacks and whites, gays and straights, left and right, pole and chinese and puerto rican and slovenian? other countries with such divisions have in fact divided into new nations with new names, but not this one, impossibly interwoven even in its hostilities.

once these disparate parts were held together by a common enemy, by the fault lines of world wars and the electrified fence of communism. with the end of the cold war there was the creeping concern that without a focus for hatred and distrust, a sense of national identity would evaporate, that the left side of the hyphen—african-american, mexican-american, irish-american—would overwhelm the right. and slow-growing domestic traumas like economic unrest and increasing crime seemed more likely to emphasize division than community. today the citizens of the united states have come together once more because of armed conflict and enemy attack. terrorism has led to devastation—and unity.

which statement best traces the development of a central idea from one paragraph to the next?