The correct option is D All of the above
Some plants such as Viola (common pansy), Oxalis and Commelina produce two types of flowers namely chasmogamous (flowers which are similar to flowers of other species with exposed anthers and stigma), and cleistogamous flowers which do not open at all. In such flowers, the anthers and stigma lie close to each other. Cleistogamous flowers are autogamous as there are no chances of cross-pollination. Thus, cleistogamous flowers produce assured seed-set even in the absence of pollinators.