The “beat generation” was the nickname for

The answer to your question is a group of writers and thinkers centered in Greenwich Village, New York City, in the mid-1950s.

Explanation:
The Beat Generation also popularly known as the Beat Movement was a literary movement in the 1950's arisen by authors who wrote about politics during the time after World War II.  Some of the best known "Beat literature" is Jack Kerouac's On the Road and Allen Ginsberg's Howl.

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Correct. A. The sentence is grammatically correct.