The vascular plants have several specialized reprodutive organs, which one responsible for one stage of the process of reproduction. The flowers are reprodutive organs, as well as fruits and cones, however they function in reproduction is distinct. The flowers is the most complex reproductive organ, since it is composed by for different structures (carpels, staments, petals and sepals), the cones are where the seeds are produced in the female plants during sexual reproduction after being fertilised by male gametes (pollen), and the fruits are the result following the pollination that are important to continuity of plants generations. Therefore, the alternative D (all of them are correct) is the answer for that question.