Perianth and no integuments
Embryo development and apical meristem
Absence of resin duct and leaf venation
Presence of vessel elements and absence of archegonia
Unlike Cycas and Pinus, Gnetum shows the presence of vessel elements and the complete absence of archegonia in female gametophyte. Thus, Gnetum shows affinities with angiosperms. It resembles angiosperms in several other aspects like the presence of tetrasporic embryo sac, free nuclear divisions in the embryo sac, two cotyledonous embryo, etc.Hence the correct option is D.