How is natural selection best defined?

Natural selection is best defined as the process by which favorable traits increase in frequency over time. This fundamental concept of evolutionary biology revolves around the idea that individuals within a population exhibit variations in their traits, some of which may confer advantages in terms of survival and reproduction in a particular environment. Over generations, individuals with these advantageous traits are more likely to survive and reproduce, passing those traits on to their offspring. As a result, those traits become more common in the population.

This process is not about arbitrary survival but rather about the differential success of individuals based on their adaptations to the environment. Traits that enhance survival or reproductive success become more prevalent, leading to evolutionary change. Thus, this option encapsulates the essence of how natural selection operates in shaping the diversity and adaptation of life forms over time.