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
The deer and plant populations increased and decreased throughout the years, but did not affect each other's population.
b
When the plant population decreased, this lead to a significant increase in the deer population.
c
When the deer population increased significantly, the plant population decreased in response.
d
The plant population increased dramatically in response to an increase in the deer population.