What are the fixed alleles in the human species?
O A. The alleles that no one has
OB. The alleles that everyone has
O C. The alleles that change most often
D. The alleles that are on the most chromosomes

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.