What type of divergent adaptation occurs when a very small subpopulation becomes separated and divergent adaptation is quick?

Of the following given choices;

(A) Allopatric Speciation

(B) Peripatric speciation

(C) Parapatric speciation

(D) Sympatric speciation

The answer is; A

This type of speciation occurs when a subpopulation of a population is isolated from the rest of the group either by geographical features such as mountains, valleys, and etcetera. The subpopulation is unable to mate randomly with the rest of the population and hence adapt slowly to their local environment. This, over time, causes reproductive isolation of the subpopulation from the rest of the population hence evolving into a new species.