In 1990, what was the population density near chicago?
a.
6 or fewer people per square mile
b.
18-45 people per square mile
c.
45-90 people per square mile
d.
90 or more people per square mile

Mexico city is an example of how humans alter their environment because it was a. one of the world’s largest cities b. built on drained and filled lake beds c. built after conquest by the spanish d. once the capital of the aztec empire