The process by which organisms best suited to their environment survive and reproduce is known as?

The correct answer is natural selection, which refers to the mechanism by which certain traits that enhance survival and reproductive success become more common in a population over generations. This concept, introduced by Charles Darwin, emphasizes the role of environmental pressures in determining which individuals thrive based on their genetic traits. Organisms that are better adapted to their environment tend to survive longer and produce more offspring, thereby passing on their advantageous traits to the next generation.

While the other terms relate to evolutionary processes, they do not capture this specific mechanism as effectively. Genetic drift involves random changes in allele frequencies that can lead to significant changes in a population’s genetic makeup over time, primarily due to chance events rather than adaptation to the environment. Adaptive evolution encompasses broader changes that occur when organisms adapt to their environment, but it does not pinpoint the survival and reproduction aspect as distinctively as natural selection does. Similarly, "survival of the fittest," although commonly associated with natural selection, is a phrase that summarizes the idea rather than explaining the underlying process systematically. Natural selection is the foundational principle that describes how advantageous traits guide the survival and reproduction of organisms within a specific ecological context.