The first is red cell (erythrocyte) the second is white cell (leukocyte)
b) Which organelle is missing in the red blood cell?
c) Describe a feature that shows the difference between a red blood cell and other cells in the human body.
d) Explain how red blood cells are adapted to perform their function.
e) Describe the functions of white blood cells.
plzz plz help plz

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.