During the period of industrialization in the United States, which primarily spanned from the late 19th century to the early 20th century, the region that received the most immigrants was the Northeast, particularly cities like New York City and other industrial centers. Therefore, based on typical regional designations, if "Region 1" refers to the Northeast, then that would be the correct response.
However, without the specific definitions for "Region 1," "Region 2," "Region 3," and "Region 4," it is challenging to provide a definitive answer. If you can provide more information about what each region represents, I can help you identify the correct one.