Which selection occurs when natural selection favors one extreme variation of a trait?

Directional selection occurs when natural selection favors one extreme variation of a trait, leading to a shift in the population's characteristics over time. This process typically results in individuals with traits that are more advantageous in a specific environment being more likely to survive and reproduce. For example, if a population of animals experiences changes in their environment that favor larger body size for survival, those individuals with larger sizes would be selected for, causing the average size within the population to increase over generations.

The other types of selection differ in their mechanisms. Stabilizing selection favors the average traits while selecting against extremes, maintaining the status quo of traits in the population. Disruptive selection, on the other hand, favors extreme variations at both ends of the trait spectrum and can lead to a split in the population. Adaptive selection is a broader term that refers to any selection process that enhances the fit of organisms to their environment but does not specifically describe favoring one extreme variation. Thus, the selection process described in the question aligns with directional selection.