Ans ) B)25%
Explanation : Female is carrier of colorblindness and the male with whom se bears a child is normal .
Now, we know colourblindness is a 'x' linked disease.
Female will produce two gametes one for normal 'x' and other 'x' which is carrier for recessive trait.
And male will produce one 'x' and one 'y' gamete.
Here 50% individual will be female who may or may not be carrier but can never be affected or colorblind
And among male individuals who are formed because male parent will share its 'y' chromosome has 50% chance of being colorblind. So chance of getting affected progeny is 50% of 50% i.e. 25%.
Hope it helps!!!