Answer:
The correct answer is - directional selection.
Explanation:
In a population, if a particular phenotype is favored among all others in every individual by continuously shifting the allele frequency towards one direction only, this type of selection called directional selection. It is a mode of natural selection.
In this case, the finch population will change towards the directional selection due to the food source become similar for both small and large-billed due to climatic change in the long term all seeds become soft so the small billed will be more favored.
