Answer:
b. disruptive selection
Step-by-step explanation:
Disruptive selection's graph has two peaks with a valley in the middle instead of the bell curve having one peak in the middle.
The shape comes from the fact that both extremes are selected for during disruptive selection. The median is not a favorable trait in this case. Instead, it is desirable to have one extreme or the other, with no preference over which extreme is better for survival. This is the rarest of the types of natural selection.