If in the second generation you still got some white flowers, what should you do next to get a colored pure-bred plant?
a. Nothing, there is no way to get a purebred from this experiment.
b. Choose several of the colored flower plants, self-fertilize them, then plant and grow the seeds.
c. Choose several of the white flower plants, self-fertilize them , then plant the seeds. If you get colored offspring you know that they are purebred.