How do the Sun's luminosity and apparent brightness compare with those of other stars? O A. The Sun's luminosity is average, and it has the least apparent brightness B. The Sun's luminosity is above average, and it has the greatest apparent brightness. O C. The Sun's luminosity is average, and it has the greatest apparent brightness O D. The Sun's luminosity is below average, and it has the least apparent brightness.

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.