Refer to the Figure

Refer to the figure.
The figure shows results from a study by Hudson and colleagues on red grouse and their nematode parasite. The figures show the cycling of six red grouse populations subjected to three treatments: (A) two control populations, (B) two populations treated for nematode parasites in 1989, and (C) two populations treated for parasites in 1989 and 1993. Each of the six grouse populations is designated by a different color. These results show that removal of the parasite

A) caused host populations to collapse.
B) reduced the fluctuations of the grouse population.
C) increased the fluctuations of the grouse population.
D) halted population cycles in the red grouse.