Read this passage from "The City Without Us" by Alan Weisman:
Within two centuries, estimates Brooklyn Botanical Garden
vice president Steven Clemants, colonizing trees will have
substantially replaced pioneer weeds. Gutters buried under
tons of leaf litter provide new, fertile ground for native oaks
and maples from city parks. Arriving black locust and
autumn olive shrubs fix nitrogen, allowing sunflowers,
bluestem, and white snakeroot to move in along with apple
trees, their seeds expelled by proliferating birds.
Which statement best explains how the structure of the passage supports the
author's purpose?
A. The passage shows the effect of natural forces such as seed
dispersal to highlight how plants become established in different
areas.
O B. The passage lists the varieties of plant life to show the biodiversity
of the city because of human intervention.
C. The passage traces the chronology of the biological succession of
plants to predict that the city will become an oasis fit for human
habitation.
O D. The passage traces the chronology of the biological succession of
plants to highlight how an urban area will return to its natural
state.