The correct answer is option 3. Colour-blind individuals have difficulty distinguishing between certain colors, particularly red and green. This is because they lack or have a deficiency in the photopigments that are responsible for detecting these colors in the retina of the eye. As a result, they may perceive red and green as similar or even identical shades.

Option 1, yellow and white, does not apply to colour-blindness as these colors are typically distinguishable for individuals with normal color vision. Option 2, green and blue, is also not applicable as these colors are typically distinguishable for most individuals, regardless of color-blindness. Option 4, black and yellow, is unrelated to color-blindness as it involves a difference in brightness rather than color perception.

In summary, colour-blind individuals typically struggle to distinguish between red and green colors.