If a colourblind woman marries a normal visioned man, their sons will be -

The correct option is D All colourblind

Colourblindness is a disease in which a person is unable to differentiate between red and green colour. The gene for this disease is located on the X-chromosome. So, if a colourblind woman marries a normal man, it will produce all the sons colourblind.

So, the correct answer is 'All colourblind'.