$A$ normal-visioned woman, whose father is colour-blind, marries a normal-visioned man. What would be the probability of her sons and daughters being colour-blind? Explain with the help of a pedigree chart.

(D) The woman is a carrier for colour blindness because her father was colour-blind (genotype $X^c Y$). She inherited the $X^c$ chromosome from her father, so her genotype is $X^C X^c$. The man is normal-visioned, so his genotype is $X^C Y$.
Cross: $X^C X^c$ (woman) $\times$ $X^C Y$ (man)
Offspring genotypes:
$1$. $X^C X^C$ (Normal-visioned daughter)
$2$. $X^C X^c$ (Carrier daughter, normal vision)
$3$. $X^C Y$ (Normal-visioned son)
$4$. $X^c Y$ (Colour-blind son)
Probability:
- Daughters: $0 \%$ chance of being colour-blind ($50 \%$ are carriers).
- Sons: $50 \%$ chance of being colour-blind.