Which of the following best describes natural selection?

Natural selection is best described as the process by which certain traits become more common in a population over time because they provide individuals with advantages in their environment. This concept, often summarized as "survival of the fittest," highlights how organisms with favorable traits—those that enhance their ability to survive and reproduce—are more likely to pass on their genetic material to the next generation.

This process is not random; rather, it's a consistent and observable outcome of the interactions between organisms and their environment. For example, in a population of animals, those with better camouflage may evade predators more effectively, thus having a greater chance of survival and reproduction. As these advantageous traits are inherited, they become more prevalent in future generations, shaping the evolution of species.

The other options do not accurately capture the essence of natural selection. Random variations do occur in populations, but these variations alone do not constitute natural selection. The notion of only the "strongest" species being selected overlooks the complexities of adaptation and fitness, which depend on various environmental factors, not merely strength. Lastly, while methods used in agriculture, like selective breeding, are related to the principles of natural selection, they represent human intervention rather than the natural process itself.