Answer: B. strong natural selection.
Explanation:
Speciation is the process by which new species form from the existing parent species. It occurs when the population of the species become reproductively isolated. In sympatric speciation the organisms living in the same geographical area becomes reproductively isolated due to changes in the behavior, morphology and genetic make up.
Among the option given, strong natural selection is the correct option. This is because of the fact that natural selection brings changes in the living being in terms of adaptation. The organism having better phenotypic trait will survive and reproduce. The beneficial traits will pass on to next generation may lead to evolution of new species. The members of the new species may not be able to breed with parent species.
