Question

A colorblind man married with a daughter of a color-blind father, the generation will be
A. all children will be colorblind
B. only sons will be colorblind
C. only daughters will be colorblind
D. half sons will be colorblind

Answer 1

Color blindness is the disease in which a person is unable to distinguish one or more colors of the eyes, and it is sex-linked genetic diseases that mainly affect males mostly than females.

Complete answer: Generally in humans, this disease is inherited, where the genes that are present on the cones of eyes that are responsible for color vision are defective.
This color blindness X-linked disease, where that color-blind defective gene is transferred from parents to offspring.
In the above question, they mentioned that colorblind man, as we know that it is X linked, so in males, only one X chromosome is present which means one gene causes the disease if it is dominant.
So color-blind male married to the daughter of color-blind father, as we know that daughter always obtain X chromosome from father, so the color blind genes from father are transmitted to daughter, but their won’t be any phenotypic expressions as there is another X chromosome which masks the disease, but this daughter is present as carrier.
So the sons of color-blind father and carrier mother have probability where half of sons' progeny may present as color blindness.
So the correct option is D.

Note: Color blindness are mainly occurs in males, it is because they have only X chromosome, the gene responsible for color blindness if transmitted, there will be phenotypic expression, but for the female to produce the color blindness, where both X chromosomes should have dominant genes for color blindness, even single makes them carrier but not shows the phenotypic expression.