$A$ condition characterized by not having an exact number of chromosomes in a diploid set is called

Loss or gain of a segment of $DNA$ results in

Select the incorrect statement regarding Down's syndrome.

Due to non-disjunction of chromosomes during spermatogenesis,sperms carry both sex chromosomes $(22A + XY)$ and some sperms do not carry any sex chromosome $(22A + O)$. If these sperms fertilize normal eggs $(22A + X)$,what types of genetic disorders appear among the offspring?

$A$: Turner's syndrome generally does not occur in males.
$R$: Foetus with $44 + YO$ complement generally dies.

Match List-$I$ with List-$II$ : Choose the correct answer from the options given below :

List-$I$	List-$II$
$A.$ Down's syndrome	$I.$ $11^{th}$ chromosome
$B.$ $\alpha$-Thalassemia	$II.$ $X$ chromosome
$C.$ $\beta$-Thalassemia	$III.$ $21^{st}$ chromosome
$D.$ Klinefelter's syndrome	$IV.$ $16^{th}$ chromosome