Cabbage, broccoli, cauliflower are obtained from wild cabbage by

• In its uncultivated form, Brassica oleracea is known as wild cabbage. The family incorporates cabbage, kale, collards, cauliflower, broccoli, kohlrabi etc.,
• Artificial selection may be a process in which humans consciously select for or against particular features in organisms.
• Artificial selection has enabled the cultivation of latest crops with desirable traits from one single common ancestor. 
• Furthermore, once a plant with the mixture of alleles for a desired phenotype is produced, it is often propagated asexually by taking cuttings, grafting and inspiring runners or through layering. 
• By artificial selection, man has produced many crop plants like broccoli, cabbage, cauliflower, kohlrabi etc. from a standard wild cabbage species by selective breeding and artificial selection.

Hence, the correct answer is option C.