You begin an experiment with two populations of E. coli that are each composed of 100 cells. The cells are genetically identical (i. e., they are clones). You grow these population in flasks on a lab bench under identical conditions with unlimited resources. Which of the following statements about the populations is TRUE? A) Natural selection begins operating immediately on the population B) Initial differences in the population will be the result of sexual selection. C) Initially mutation will be the only source of variation in the population. D) After 100 generations both populations will still be genetically identical because they have accumulated the same mutations over time. E) Both C and D are true.