Both husband and wife have normal vision though their fathers were colour blind. The probability of their daughter becoming colour blind is?

The correct option is A $0\%$

If both husband and wife have normal vision when their fathers are colorblind then, the husband has normal vision while the wife is a carrier of the colorblind gene, that is located on the X chromosome. This would result in one normal and one carrier female progeny, both being phenotypically normal.

So, the correct answer is'0%'