Answer:
Stabilizing selection
Explanation:
Stabilizing selection is the most common form of natural selection that is not easy to notice in a population as the change is less drastic. It occurs when average or intermediate phenotypes of a trait in a population are favored, while the extreme phenotypes of that trait are not favored by the forces of natural selection. Over time, intermediate or non-extreme traits become more common in the population, while extreme traits become less common.
There are 4 outer atoms and lone pairs that are present in a molecule with a see-saw shape. It was called "seesaw" comes from the observation that it looks like a playground seesaw. It is very common that four bonds to a central atom result in tetrahedral or, less commonly, square planar geometry.