Natural selection is best described as which process?

• A. A random change in allele frequencies in a population.
• B. A process where heritable traits that increase survival and reproduction become more common.
• C. Acquired traits are inherited.
• D. An organism actively choosing beneficial traits.

Answer: (B)

Natural selection describes how heritable traits that help an organism survive and reproduce become more common over generations. In any population, there’s variation in traits, and some of that variation is passed down to offspring. If a trait provides a survival or reproductive advantage in a given environment, individuals with that trait tend to leave more offspring, increasing the trait’s frequency in the population over time. This differential success leads to adaptation to the environment.

The other ideas don’t fit natural selection. A describes random changes in allele frequencies due to chance, not driven by fitness differences. C suggests that traits acquired during an organism’s life are inherited, which isn’t how genetics works. D implies organisms actively choosing traits, which isn’t how evolution operates—the process is not guided by conscious choice but by differential reproduction based on existing variation.