Which of the following is a Mendelian disorder?

Write a short note on Haemophilia.

$A$ haemophilic man marries a normal woman. Their offspring will be:

Autosomal dominant disorder $- P$
Autosomal recessive disorder $- Q$
$X$-linked recessive disorder $- R$
$I -$ Haemophilia,$II -$ Sickle cell anaemia,$III -$ Phenylketonuria,
$IV -$ Thalassaemia,$V -$ Colour blindness,$VI -$ Myotonic dystrophy
Select the correct option for $P, Q$ and $R$.
$\quad\quad P \quad\quad Q \quad\quad R$

One way of detecting sex-linked inheritance is:

Give scientific reasons: The human male never passes on the gene for haemophilia to his son.