The megasporangium is equivalent to which structure in angiosperms?

The three cells present at the chalazal end form $.....P......$,and the three cells present at the micropylar end form $.....Q.....$.
$\quad\quad\quad \quad \text { P } \quad\quad\quad \text { Q }$

Synergids of the $Polygonum$ type embryo sac are

Which of the following is a part of the pistil (gynoecium)?

The arrangement of nuclei in a typical angiosperm embryo sac is ......... .

In which of the following is the gametophyte retained within the sporophyte?