Answer:
16. Directional Selection
17. Disruptive Selection
18. Stabilizing Selection
19. Natural Selection
20. Adaptation
Explanation:
In population genetics, directional selection/positive selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes.
Disruptive Selection would show phenotypes (individuals with groups of traits) of both extremes but have very few individuals in the middle.
Stabilizing Selection. Occurs when individuals at the extremes of the range of characteristic are selected against. This means that the "average" individuals are selected for.
