By the 1920s the "Red Scare" was just below the surface of American society but the immigration of people from this part of the world was becoming a major concern.

In the 1920s, many Americans associated political radicalism and the Red Scare with immigrants from Eastern and Southern Europe. Immigration from those regions became a major concern and contributed to restrictive laws such as the quota system established in 1924. Therefore, the correct choice is Eastern and Southern Europe.

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