Sandra is heterozygous for eye shape. What does this mean?

O She has two of the same alleles for eye shape, one from each parent

O she has two different alleles for eye shape, one from each parent

O She has only one allele for eye shape, which she received from one parent

O She has two alleles for eye shape, both from the same parent

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.