Identify the given figure and select the correct option.
$\quad\quad\quad P\quad\quad Q$

Which disorder is caused by the loss of one $X$ chromosome in females?

Absence or excess or abnormal arrangement of one or more chromosomes results in

The condition in which there are more than two complete sets of chromosomes is called:

Mongolism syndrome is caused by

Three copies of chromosome-$21$ in a child with Down's syndrome have been analysed using molecular biology technology to detect any possible $DNA$ polymorphism with reference to different alleles located on chromosome-$21$. Results showed that out of $3$ copies,$2$ of the chromosomes of the child contain the same alleles as one of the mother's alleles. Based on this,when did the non-disjunction event most likely occur?