"Natural selection" is a process by which

A) favorable traits become increasingly common in a population of interbreeding individuals, while traits that are unfavorable become less common.
B) animal breeders select animals in each generation that have the most "natural" traits to breed the next generation.
C) favorable traits become increasingly common in a population over the course of a single generation.
D) genetic mutations lead to random changes within a population of organisms.

Answer: A
Rationale: Natural selection is the process by which favorable traits become increasingly common in a population of interbreeding individuals, while traits that are unfavorable become less common. This is generally a very slow process and does not occur in a single generation.