Which of the following plants has orthotropous ovules?

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:

Select the incorrect statement regarding the Megaspore Mother Cell $(MMC)$.

In the given figure,what do 'a','b',and 'c' represent respectively?

The female gametophyte of a typical dicot at the time of fertilization is

Explain the structure and development of the embryo sac.