Why has mexico’s birth rate decline started much more recently than sweden’s?

Plsss > .< compare and contrast the characteristics of flatworms rounds worms and earthworms

Which prefix mean under less or below

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.