Female gametophyte of angiosperm is represented by $-$

Which part of the pistil serves as a landing platform for pollen grains?

In a typical angiosperm,how many female gametophytes develop within a single megasporangium?

What do '$d$' and '$e$' represent in the given figure?

$A$ mature Polygonum-type embryo sac contains:

Choose the correct sentence$(s)$.
$(I)$ Nucleus of the functional megaspore divides meiotically to form two nuclei.
$(II)$ After the $8$-nucleate stage,cell walls are laid down leading to the organization of a typical female gametophyte.
$(III)$ The egg apparatus consists of two synergids and one egg cell.
$(IV)$ Three cells at the chalaza end are called antipodal cells.