During the Winter of 1999, Minimum Temperatures Did Not Get

During the winter of 1999, minimum temperatures did not get much below freezing in an Oregon pond, and the following summer, large mosquito populations were observed. In the winter of 2000, frost came early and most ponds were frozen for 3 months. The following summer, very small mosquito populations were observed. This is an example of

A) community carrying capacity.
B) density- dependent regulation.
C) exotic regulation.
D) ecosystem carrying capacity.
E) density- independent regulation.