Refer to the Figure

Multiple Choice

Refer to the figure.
The figure represents the results of an experiment by Vredenburg, who compared the numbers of frogs in several categories of lakes: lakes never having trout (control) , lakes having trout (control) , and lakes from which he removed trout at different times. He observed changes in frog populations over eight years in all lakes. Based on evidence from the figure, which conclusion can be made about the effect of trout removal on frog populations?

A) Frog populations in some lakes overpopulate after the removal of trout.
B) Frog populations increase in some removal lakes but not in others.
C) Frog populations never recover once trout have been introduced.
D) Frog populations begin to recover once trout are removed.