The correct answer is A. Green & Red.
Color blindness is a condition in which people have difficulty distinguishing between certain colors. The most common type of color blindness is red-green color blindness, which affects about 8% of males and 0.5% of females. People with red-green color blindness have difficulty distinguishing between red and green, and may also have difficulty distinguishing between other colors that are similar to red and green, such as brown and orange.
There is no cure for color blindness, but there are ways to manage it. People with color blindness can learn to identify colors by their brightness or by their position in the spectrum. They can also use special glasses or contact lenses that can help them to see colors more accurately.
The other options are incorrect because they are not colors that are typically difficult for people with color blindness to distinguish. White and red are both primary colors, and blue and red are both secondary colors. Black is not a color, but rather the absence of color.