The theme of alienation and the struggle against conformity and against limits on free expression was at the heart of the american literary movement known as the a. abstract expressionist movement. b. harlem renaissance. c. rebel without a cause movement. d. beat generation

Abstract Expressionist Movement: Post WWII, Newyork, 1940s, trying to put NY at center of art in western world.
Harlem Renaissance: Name for social/cultural/artistic "boom" or "explosion" in Harlem from the ending of WWI-1930s.
Rebel Without A Cause: It's a movie, they just added "Movement" to the end.
Beat Generation: A group of authors who explored and influenced political and cultural ideas after WWII.
I'd say it's most likely A.