Starting from the Wild Mustard Brassica Oleracea, Plant Breeders Have

Starting from the wild mustard Brassica oleracea, plant breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Which of the following statements is correct with regard to the wild mustard?

A) There is enough heritable variation in the wild mustard to permit these different varieties.
B) Heritable variation is low in wild mustard-otherwise this wild strain would have different characteristics.
C) Natural selection is rare in wild populations of wild mustard.
D) In wild mustard, most of the variation is due to differences in soil or other aspects of the environment.