The Most Important Reason That the Chicago School's Main Laboratory

Multiple Choice

The most important reason that the Chicago School's main laboratory for sociological research was the city of Chicago itself was that:

A) travel at that time was expensive,so fieldwork in Chicago was convenient.
B) it was an American city,and trends in America were very similar to global trends.
C) Chicago is in the American Midwest,and the center of the country was seen as a composite of all American cities.
D) industrialism,immigration,and increasing ethnic diversity in Chicago were all interesting trends for sociologists to study.