In the USA the frequency of carriers for the devastating autosomal recessive trait of procrastination is 1/10 people. You do not procrastinate and want to have a child with another highly efficient non-procrastinator. You are worried that you both might be carriers and that your child would be a procrastinator. What is the probability that you are a carrier, AND your mate is a carrier, AND your child is procrastinator

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.