The census of 1890 highlighted the closing of the frontier, which coincided with
A) John Muir's conservation activities.
B) Rachel Carson's Silent Spring.
C) the greenbelt movement.
D) the Dust Bowl.
Question 2
Pesticide-resistant insects would
A) have evolved more slowly if the pesticides were used in just a few regions.
B) not have evolved if even more pesticide had been used.
C) have evolved more quickly if a different type of pesticide was used each year.
D) have evolved if an herbicide had been used instead of a pesticide.
