What does the $Oestrous$ cycle indicate?

The most common method of asexual reproduction is by

Clones are produced by asexual reproduction and resulting individuals are identical . . . . . . .

The essential and most critical event in sexual reproduction is

Identify the haploid and diploid structures from the following:
$I$ - Zoospore,$II$ - Zygote,$III$ - Egg cell,$IV$ - Gametophyte,$V$ - Sporophyte
Haploid structures $\quad\quad$ Diploid structures

Which of the following statements is $NOT$ correct?