$A$ son of a colourblind father and a normal homozygous mother marries a daughter of a normal father and a heterozygous (carrier) mother. What will be the phenotype of their children?

Which of the following disorders can occur if the protein required for blood clotting is affected?

Study the given pedigree chart.

Select the incorrect statement with regard to haemophilia.

$A$ normal girl, whose mother is haemophilic, marries a male with no ancestral history of haemophilia. What will be the possible phenotypes of the offsprings?
$(a)$ Haemophilic son and haemophilic daughter.
$(b)$ Haemophilic son and carrier daughter.
$(c)$ Normal daughter and normal son.
$(d)$ Normal son and normal daughter.
Choose the most appropriate answer from the options given below:

Haemophilia $A$ is due to the absence of