Final answer:
The statement reflects the Melting Pot theory, which encapsulates the assimilation and cultural blending of immigrants into American society, particularly during the period of rapid urbanization in the Industrial Revolution.
Step-by-step explanation:
The historical phenomenon reflected in the statement regarding new immigrants assimilating into American culture and expanding their communities is the Melting Pot theory. This concept emerged as immigrants from varied backgrounds learned English and integrated into the broader American society, blending different cultures and norms to create a diverse, yet unified nation. The Industrial Revolution greatly accelerated urbanization, causing cities to swell with an influx of immigrants seeking work in factories and leading to the formation of ethnic neighborhoods, where people shared common cultures, languages, and traditions, yet also adopted elements of American culture.
Answer: d) The Melting Pot theory