13. TEKS: Bio.5(A) The model below represents the change in the amount of DNA in a cell during the cell cycle. DNA Content During the Cell Cycle Complete Sets of DNA in Nucleus I III IV Cell Cycle Phase

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.