After the __ - nucleate stage, cell walls are laid down leading to the organization of the typical female gametophyte or _____________.

The correct option is C 8, embryo sac
The process of formation of a mature embryo sac (female gametophyte) begins with the division of the nucleus of the functional megaspore. The two nuclei, thus formed, then undergo two more successive mitotic divisions to form eight nuclei. Thus, eight nuclei are present in a single cell. At this point, cell walls are laid down leading to the organisation of the typical female gametophyte or embryo sac.
The embryo sac is 7 celled and has eight nuclei.