In the scenario described, individuals with medium brown fur are less likely to be seen by predators, which suggests that this trait provides a selective advantage. This would likely lead to a decrease in the frequency of both light brown and dark brown mice.
Given that medium brown is favored and the extremes (light and dark) are selected against, this represents stabilizing selection. Stabilizing selection typically results in a distribution curve that has a tall, narrow peak at the center, indicating that the average trait (medium brown fur) is favored while extreme traits (light and dark brown) are less common.
Therefore, the correct response is:
stabilizing; a tall, narrow peak in the center of the graph.