In 1975 in Sweden, Mange Mites Were Found to Infest

In 1975 in Sweden, mange mites were found to infest the carnivorous red fox, causing hair loss, skin deterioration, and finally death. At its peak, this mange, specific to this fox, reduced the population of the fox by over 70 percent in Sweden. Biologists noted that hare and grouse populations increased in number by a factor of 2 to 4. Most likely, the hare population increased because:

A) competitive exclusion reduced the population of the host parasite of the hare.
B) the predator mange decreased the numbers of the main parasite of the hare.
C) the parasitic mange decreased the numbers of the main predator of the hare.
D) Both A and C are plausible conclusions.