Haemophilia is:

Sickle cell anaemia is caused due to the substitution of

$A$ person whose father is colourblind marries a lady whose mother is the daughter of a colourblind man. Their children will be:

$A$ normal woman,whose father was colour blind,marries a normal man. What is the chance of occurrence of colour blindness in the progeny (in $;\%$)?

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 $R$.
$\quad\quad P \quad\quad Q \quad\quad R$

$A$ woman with normal vision,but whose father was color-blind,marries a color-blind man. Suppose their fourth child is a boy. This boy will be ....... .