Which statement describes natural selection?

• A. Randomly changes gene frequencies regardless of environment
• B. Occurs only in small populations
• C. Favours individuals with maladaptive traits
• D. Increases fitness by favoring better-adapted individuals

Answer: (D)

Natural selection is about differential survival and reproduction based on heritable traits. In any environment, individuals with features that help them cope with pressures like predators, climate, or finding food are more likely to survive and pass their genes to the next generation. Those advantageous traits thus increase in a population over time, boosting the overall fitness of the better-adapted individuals. That’s why this statement—natural selection increases fitness by favoring better-adapted individuals—is the best description.

The other ideas don’t fit because natural selection isn’t about random changes in gene frequencies without regard to the environment (that’s genetic drift). It isn’t restricted to small populations; it can occur in populations of various sizes, though its effects can be stronger in smaller groups. And it does not favor maladaptive traits; traits that reduce survival or reproduction tend to be selected against.