Answer:
D. 90 or more people per square mile
Explanation:
Chicago and its surrounding areas have always been known to be well populated. Chicago is a business hub and one of the business capital of the United States. Job opportunities, career growth, social infastructure, industries, markets e.t.c has driven a lot of people en-masse from all over the world to Chicago and its environs.
As at 1990, the population density near Chicago was already on the high side pegged at an estimate of about 90 or more people per square mile.
