In addition to the boll weevil, what other natural disaster greatly affected cotton farmers in the 1920s?
a) a major drought
b) a locust plague
c) flooding of fields
d) severe cold weather

Among the following environmental factors, which does not have a long-term impact on the composition of a region's soil? a. kinds of crops grown b. types of fungi present c. topography of the landscape d. variety of species of mammals e. number of freezes occurring annually