Which statement about evolution is true regarding individuals and populations?

Populations evolve as a whole because evolution is defined as the change in the frequency of alleles (gene variants) within a population over time. This process occurs due to mechanisms such as natural selection, genetic drift, mutation, and gene flow. While individual organisms may undergo changes during their lifetimes, these changes are not passed on genetically to the next generation, and therefore, individuals do not evolve. Instead, it is the collective genetic makeup of a population that shifts over generations, leading to evolution at a population level.

This understanding emphasizes the importance of genetic variation within a population, as evolution relies on differences among individuals that can be acted upon by environmental pressures. Thus, the true statement accurately captures the essence of evolutionary change occurring over time at the population level rather than within individual organisms.