Solution

Ishihara colour test examines the ability of colour perception. It consists of a number of coloured plates which are called as an Ishihara plates. Each plate contains a circle of dots, random in colour and size; few dots in each plate form a number or shape that is clearly visible to the person with normal colour vision but is invisible or difficult to see to the person with impaired colour perception. Colour blindness is the inability or reduced ability to perceive colour differences under the normal lighting conditions and hence can be diagnosed with Ishihara test. A person with an eye infection does not suffer from impaired ability/disability of colour perception; thus can’t be detected with Ishihara test. A person with night blindness has impaired vision in the night or dim light; they are sensitive to light intensity, not to the colour of light and thus can’t be diagnosed with Ishihara test. The friction ridges of human finger produce impressions which are called fingerprints; the test detects the colour perception, not fingerprints. The correct option is C.