These pictures compare the numbers of prairie dogs in an area at two different times. The picture on the right shows the area 10 years after the
picture on the left.
Which statement best explains the change over the 10-year period?
A. Both the death rate and the emigration rate decreased.
B. The immigration rate remained steady, and the birthrate increased.
C. Both the emigration rate and the death rate increased.
D. The birthrate increased, and the emigration rate remained steady.