Which stage is the last stage of speciation?

The populations become adapted to different environments and eventually become so different that they cannot interbreed to produce fertile offspring.

The populations are isolated and thus do not interbreed.

The populations become totally separated from one another.

The populations interbreed successfully.

The populations become adapted to different environments and eventually become so different that they cannot interbreed to produce fertile offspring.

Speciation is the evolution of one species into two different kinds, and when they become isolated, that is the final step, since they cannot interbreed any longer.

Answer: The populations become adapted to different environments and eventually become so different that they cannot interbreed to produce fertile offspring.

Explanation:

Speciation is a process of development of new species from the parent species. This occurs when the members of the population get separated due to geographical barriers such as river, mountains and others. Or if the members of the same species diverge on the basis of morphological, physiological, reproductive and behavioral changes.

The isolated members in the end in the cases of geographical separation becomes diverge or different species as they cannot interbreed with the members of the parent species due to the adaptations according to the new environment.