Which statement best explains why US cities became segregated by culture and ethnicity in the late 1800s and early 1900s?

For edgenuity the answer is option a

Immigrants to the nation during this period started forming communities containing people of shared cultures and ethnicities. This allowed them to be able to be with people of a shared background, easing the transition into a new country and culture. The separation of persons of different backgrounds led to small "towns" springing up within larger urban centers during the late 19th century.