Use the model here to describe the transfer of matter and flow of energy from one trophic level to another within an ecosystem. All of the following must be addressed in your response to receive full credit:

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.