Give scientific reasons: In pteridophytes,the development of the zygote inside the female gametophyte is considered an important phase.

(N/A) $\rightarrow$ In pteridophytes,the female gametophyte is retained on the parent sporophyte for a variable period. The zygote develops into a young embryo within the female gametophyte. This event is a significant precursor to the seed habit,which is considered a crucial step in plant evolution.