Question

cities, such as new york and chicago, experienced great growth during this period mostly due to...
more innovators
a rise in birth rates
immigration

Explanation:

During the late 19th and early 20th centuries, major U.S. cities like New York and Chicago saw massive population growth primarily driven by waves of immigrants from Europe and other regions seeking industrial jobs. While birth rates and innovators played minor roles, immigration was the dominant factor.

Answer:

Immigration