Explanation:
In population genetics, the term evolution is defined as a change in the frequency of an allele in a population. ... The allele frequency within a given population can change depending on environmental factors; therefore, certain alleles become more widespread than others during the process of natural selection.
Answer:
The correct answer would be D. species.
Natural taxon refers to the group of organisms which exists in nature as a consequence of evolution.
In Linnaeus's system, the only natural taxon is "species".
Species refers to the group of organisms in which two organisms of opposite or appropriate genders can produce a viable offspring.