Answer:
Directional selection
Step-by-step explanation:
Directional selection, in population genetics, is also denoted as positive selection and is described as a mode of 'natural selection' whereby a particular extreme phenotype is being favored or privileged as compared to that of the other phenotypes, that often leads to the 'allele frequency' to change or shift over a period in time in the same direction of that particular phenotype.
The correct answer to the question above is directional selection.