The correct option is A Group of sporangial initial cell
In Eusporangiate ferns there is a large sporangium developed from several initial cells producing many spores. In some cases sporangium fuse to form Synangium. E.g., Psilotum, Selaginella. Eusporangiate ferns are vascular spore plants, whose sporangia arise from several epidermal cells. Typically these ferns have reduced root systems and sporangia, that produce large amounts or spores.