Identify the figure:

Which of the following is true for the $Zygotene$ stage of $Meiosis-I$?

In meiosis,the nuclear envelope and nucleolus disappear during which phase?

The number of chromosome groups at the equatorial plate in metaphase-$I$ of meiosis in a plant with $2n = 50$ shall be:

$A$: In the diplotene sub-stage,the two chromosomes of a homologous pair move away from each other.
$R$: The connection is maintained at the site where crossing over has occurred in homologous chromosomes.

In meiosis,the chromosome number becomes