HELP The distribution of phenotypes in a species can change when changing environmental conditions cause selection to occur. Which of the following best describes evidence that would indicate directional selection is occurring?

A shift in a population's frequency curve from an intermediate phenotype to an extreme phenotype

A shift toward equal distribution of all phenotype frequencies, including intermediate and extreme phenotypes

An increase in the frequency of extreme phenotypes and a decrease in the frequency of intermediate phenotypes

An increase in the frequency of intermediate phenotypes and a decrease in the frequency of extreme phenotypes