Which type of natural selection shifts a population toward one extreme phenotype?

Focus on the definition of directional selection: Directional selection occurs when environmental pressures favor one extreme phenotype over others, causing the population to shift toward that phenotype over generations.

Compare the options provided: Balancing selection maintains variation, stabilizing selection reduces variation by favoring the average phenotype, and disruptive selection favors both extremes but not the average. Directional selection is the only type that shifts the population toward one extreme phenotype.