In the 1930s, how did dobzhansky and mayr explain the origin of species?

In 1930s, Mayr and Dobzhansky illustrated the origin of species on the basis of allopatric speciation.

Explanation:

Allopatric speciation also called geographic speciation. This speciation takes place when the populations of the identical kind of species get separated because of the environmental modifications like the building of a mountain, and others. There are four kinds of speciation known that is, sympatric, artificial, peripatric, and parapatric.

if you listed your answers right then i believe your answer is b.