Answer:
Genetic variation is necessary for evolution by natural selection because it (A) results in different traits which can be selected for or against.
Step-by-step explanation:
Natural selection is a process in which organisms with certain traits are more likely to survive and reproduce, while those with less advantageous traits are less likely to survive and reproduce. This results in the survival of the fittest and the evolution of new species over time. Without genetic variation, there would be no differences in traits and therefore no way for natural selection to occur.