National League for Nursing (NLN PAX) Practice Exam

The correct answer is natural selection, which is a cornerstone of Charles Darwin's theory of evolution. Natural selection explains how certain traits become more prevalent in a population over generations. It operates on the principle that individuals with characteristics that are better adapted to their environment have a higher chance of survival and reproduction. As these advantageous traits are passed on to offspring, they become more common in the population, leading to the gradual evolution of species.

While genetic mutations provide the raw material for evolutionary change by introducing variations in the gene pool, it is through natural selection that certain mutations are favored or disfavored based on their impact on survival and reproduction. Environmental changes can influence which traits are advantageous at any given time, but the mechanism by which evolution operates is primarily through natural selection. Artificial selection, on the other hand, is a process driven by human intervention to breed certain traits, which is distinct from the natural processes outlined in Darwin's theory.