Identify the mismatched pairs:
$\begin{array}{ccc}& \text{Disorder}& \text{Characteristic feature}\\ i.& \text{Haemophilia}& \text{Sex linked recessive}\\ ii.& \text{Down's syndrome}& \text{Trisomy 21}\\ iii.& \text{Turner's syndrome}& \text{Trisomy of sex chromosome}\\ iv.& \text{Klinefelter's syndrome}& \text{Monosomy of sex chromosome}\end{array}$

The correct option is D iii, iv
Haemophilia is a sex-linked recessive genetic disorder (X-linked) which is characterised by impaired blood clotting.

Down’s syndrome is characterised by trisomy of the ${21}^{st}$ chromosome (three copies of ${21}^{st}$ chromosome instead of two copies per cell). It is a chromosomal disorder.

Turner’s syndrome is characterised by the absence of a copy of the X chromosome in females. A chromosomal disorder in which a single chromosome is missing is called monosomy.

Klinefelter’s syndrome is characterised by the presence of an additional X chromosome in the males. Hence, the affected individuals have three copies of sex chromosomes (XXY) and this condition is called trisomy.