Answer:
The correct answer is A. stabilizing selection
Step-by-step explanation:
Stabilizing selection is one type of natural selection that occurs when the population having non-extreme traits are stabilized. It results in overexpression of a particular trait in a population. Here most average individual gets selected.
So as the stabilizing selection favors the middle phenotype and not extreme phenotypes it decrease the genetic variation. So here individuals who are having extremely long snout are selected therefore a particular trait is selected and overexpressed in the population. So it is an example of stabilizing selection.