The number of mitotic generations required to form a mature embryo sac in most of the flowering plants is

An ovule is equivalent to:

$A$ - Four cells are at the chalazal end and are called the antipodals.
$R$ - $A$ typical angiosperm embryo sac,at maturity,though $8$-nucleate is $7$-celled.

Crassinucellate ovules possess.........

An orthotropous ovule is one in which the micropyle and chalaza are:

In angiosperms,the following events occur during megasporogenesis and megagametogenesis:
$(i)$ Differentiation of megaspore mother cells
$(ii)$ Meiosis of the megaspore mother cell
$(iii)$ Formation of a linear tetrad
$(iv)$ Mitotic division of the functional megaspore
$(v)$ Degeneration of $3$ megaspores
$(vi)$ Formation of embryo sac
$(vii)$ Fusion of polar nuclei
The correct sequence is: