Final answer:
Natural selection is the process by which organisms with traits that better enable them to adapt to their environment tend to survive and reproduce. It acts on the population's heritable traits, selecting for beneficial alleles and against deleterious alleles.
Step-by-step explanation:
Natural selection is the process by which organisms with traits that better enable them to adapt to their environment tend to survive and reproduce in greater numbers. It acts on the population's heritable traits, selecting for beneficial alleles that increase their frequency and selecting against deleterious alleles. Natural selection is not random, as it favors variants that are better able to survive and reproduce.