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Diffusion and osmosis are forms of passive transport

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.

During dna replication,each strand of dna is used as a template to produce a complementary strand of dna. this process is shown below. which base will attach to location