What happens to phenotypes in a population over time due to natural selection?

Natural selection plays a critical role in shaping the phenotypes of a population over time by acting on the variation of traits within that population. When certain traits provide a survival or reproductive advantage in a given environment, individuals with those advantageous traits are more likely to reproduce and pass those traits on to the next generation. As a result, these traits become more prevalent in the population, leading to changes in the overall phenotype, which reflects the adaptations that have been favored by natural selection.

Over generations, this process can lead to the emergence of new traits or the modification of existing ones as the environment changes, impacting the fitness of different phenotypes. Thus, the correct answer highlights that phenotypes are dynamic and influenced by the continuous selective pressures in their environment, demonstrating evolution in action.