What is the process of transferring blood from one person to another?

What is the correct trna sequence that would match the following mrna sequence.gcgaua

Number and variety of living organisms includes genetic, species, and ecological types

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.