Science PSSA Practice Test 2025 – Your Comprehensive All-in-One Guide to Exam Success!

Natural selection is the process whereby individuals with favorable traits are more likely to survive and reproduce in their specific environments. This mechanism is a key driving force behind evolution, as it enables certain traits to become more common in a population over time. These favorable traits can enhance an organism's ability to find food, escape predators, or adapt to changing environmental conditions, ultimately increasing their chances of survival and reproductive success.

In contrast, the other options represent different concepts. Genetic drift refers to random changes in allele frequencies in a population, often due to chance. Evolution encompasses the broader changes in species over time, which can occur through various mechanisms, including natural selection. Adaptation is the process through which species develop traits that enhance their survival; it is often a result of natural selection over generations, rather than the mechanism itself.