On Isle Royale, wolves are the main predators of moose. The graph shows the changing wolf and moose populations on the island over a 50-year time span. The graph plots the populations of moose and wolves in separate lines from 1955 to 2005. The two populations appear to follow opposite trends: when one population is higher, the other population is lower.

Which statement provides the strongest explanation for the trends in the two populations?

A. The populations of predators and prey are limited by abiotic factors only.
B. Predation acts a density-dependent limiting factor on prey, but not on predators.
C. Predation acts as a density-independent limiting factor on predators, but not on prey.
D. Predator-prey relationships act as density-dependent limiting factors on both predators and prey.