Why does regionalism occur in the United States?

The emergence of new regionalism coincided with the end of the Cold War and a period of increasing global economic integration. Its development ultimately led to regional organizations that were more open with respect to trade than those that had formed in the era of old regionalism.

Explanation:

the answer should be b.

explanation:

it should be b because she researched before writing so it would be in past tense. "the author researches her subject before she had written the first draft.