Over several years, biologists in a wildlife management area studied changes in the populations of deer and the plants they eat. They created a graph of their data, shown below.
Which statement best describes how deer affected the plant population over the course of the study?
A. When the deer population increased significantly, the plant population decreased in response.
B. The plant population increased dramatically in response to an increase in the deer population.
C. The deer and plant populations increased and decreased throughout the years, but did not affect each other's population.
D. When the plant population decreased, this lead to a significant increase in the deer population.