Which type of abnormality is seen in the given pedigree chart?

Albinism is a congenital disorder resulting from the lack of the enzyme:

Phenylketonuria $(PKU)$ is an inborn error of metabolism caused by the expression of recessive genes $(pp)$. In this condition,the amino acid phenylalanine is not converted into which amino acid,and what type of genetic disorder is it?

The given pedigree chart shows which type of inheritance?

$A$ woman has normal vision but some of her sons and daughters are colorblind. What are the genotypes of the woman and her husband?
$(A)$ Woman: $X^C X^C$, Husband: $X^c Y$
$(B)$ Woman: $X^C X^c$, Husband: $X^c Y$
$(C)$ Woman: $X^C X^c$, Husband: $X^C Y$
$(D)$ Woman: $X^c X^c$, Husband: $X^C Y$

Sickle-cell anaemia has not been eliminated from the African population because it