Which of the following is correct about the genetic variation observed in these populations?
a) It is created by the direct action of natural selection.
b) It arises in response to changes in the environment.
c) It must be present in a population before natural selection can act upon the population.
d) It tends to be reduced when diploid organisms produce gametes and reproduce.
e) A population that has a higher average heterozygosity has less genetic variation than one with a lower average heterozygosity.