Read the given passage and answer the following questions:

Colour Blidness is a sex-linked disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour. This defect is due to mutation in certain genes present in the X chromosome. It occurs in about 8 per cent of males and only about 0.4 per cent of females. This is because the genes that lead to red-green colour blindness are on the X chromosome.

Rahul and Shipra are husband and wife and both are suffering with colour blindness. What is the chance that their daughter will have colour blindness?

100%

The correct answer is Option (2)- 100%

Color blindness is an X-linked recessive disorder. Since both Rahul and Shipra are color blind, let's analyze their genetic contribution:

• Rahul (the father) has color blindness, which means he carries the affected gene on his only X chromosome. His genotype is X^cY (X^c = X chromosome with the color blindness gene, Y = normal Y chromosome).
• Shipra (the mother) also has color blindness, meaning she has the affected gene on both of her X chromosomes. Her genotype is X^cX^c.

For their daughter, she will inherit one X chromosome from each parent:

• She will inherit X^c from Rahul (since he only has one X chromosome).
• She will inherit X^c from Shipra (since both of Shipra's X chromosomes carry the color blindness gene).

Thus, the daughter's genotype will be X^cX^c, meaning she will definitely have color blindness. Therefore, the chance is 100% that their daughter will be color blind.