Many Times Species Are Composed of Networks of Distinct Populations

Many times species are composed of networks of distinct populations called metapopulations.When do metapopulations occur?

A) When a population is large and uniformly distributed.
B) When a population in poor habitat continually sends out dispersers to bolster populations in better habitats.
C) When a population in a better habitat does not send out colonizers into less suitable habitats.
D) When suitable habitat is patchily distributed and separated by areas of unsuitable habitat.