The reading uses several examples to demonstrate changes in the natural environment of the United States. Which of the following examples was not referenced? a. Wind eroded topsoils, which takes several years to regenerate
b. Earthquakes and volcanic activity reshape the landscape
c. Forests have been cut down and soils have eroded away.
d. In just the twentieth century, temperatures rose by one degree Fahrenheit
e. European American settlers changed the patterns of vegetation and soil