In a population, a shift in the average population phenotype toward the mean and away from the physical extremes. this process lowers phenotypic variety; the population is more homogeneous.

The correct answer would be stabilizing selection.

The stabilizing selection is a type of natural selection in which the phenotype towards mean value get stabilizes instead of extreme values.

It uses negative selection to remove the extreme values of the phenotype.

For example, in humans, the intermediate birth weight of babies is selected by stabilizing selection. The extreme weights (whether minimum or maximum) reduces the chances of survival of the offspring.

Similarly, plants with intermediate height tend to survive the most. Plants with short height do not receive enough sunlight and plants which are extremely tall are vulnerable to winds.

i might be wrong but i think its a. let me know if i’m right and have a good rest of your day!