Which of the following most appropriately describes haemophilia?

$A$ normal-sighted man, whose father was color-blind, marries a woman whose father was also color-blind. They have their first child as a daughter. What is the probability that this child will be color-blind (in $\%$)?

Which of the following is associated with sex-linked inheritance?

Match the following symbols used in Pedigree analysis:

Column-$I$	Column-$II$
$a.$ Solid symbol	$(i)$ Carrier of sex-linked trait
$b.$ Horizontal line between symbols	$(ii)$ Offspring
$c.$ Horizontal line above the symbols	$(iii)$ Affected individual (Trait to be studied)
$d.$ Dot in centre	$(iv)$ Mating (Parents)

The gene for haemophilia is located on the $X$ chromosome. Hence,it is normally impossible for a:

Thalassemia and sickle cell anaemia are caused due to a problem in globin molecule synthesis. Select the correct statement.