Which of the following statements best describes natural selection?

Natural selection is a fundamental mechanism of evolution and is best defined by its capacity to favor traits that enhance an organism's survival and reproductive success. This process operates on the principle that individuals with advantageous traits are more likely to survive and reproduce in a given environment, passing those beneficial traits on to future generations. Over time, this can lead to an increase in the frequency of those advantageous traits within a population.

The concept is rooted in the idea that variations among individuals in a population—the result of genetic mutations and recombinations—can lead to differences in physical characteristics, behaviors, or other attributes that affect survival and reproduction. When environmental pressures are applied, such as competition for resources or predation, individuals with traits better suited to their environment will thrive, while others may not.

This definition of natural selection highlights its non-random nature; it is driven by the relationship between traits and environmental conditions, rather than occurring randomly. It also emphasizes that natural selection acts on existing variation; it does not create new traits but rather selects from the traits present in the population. Consequently, while it can lead to significant evolutionary changes over time, these shifts occur gradually rather than instantaneously across entire populations, and it does not eliminate all unfavorable traits, as some may persist without significantly