The correct option is C Selaginella
In addition to being, the most "primitive" extant heterosporous genus, a member of the most "primitive" strobilate group; Selaginella shows another important evolutionary step. When megaspores germinate on the ground, the resulting megagametophyte does not leave the megaspore; rather, it is retained throughout its development within the megasporangial wall. This endoscopic development is considered to be a significant evolutionary trend toward further protection of the megagametophyte.