Which disorder is characterised by the failure to distinguish between…

The correct answer is Option (2) → Colour blindness

Colour blindness is a sex-linked recessive disorder. A defect in either the red or the green cone of the eye means the person cannot tell red from green. The genes involved lie on the X chromosome, so it is far more common in males (about 8 per cent) than in females (about 0.4 per cent). Haemophilia affects blood clotting, while sickle-cell anaemia and thalassemia are disorders of haemoglobin; none of them affects colour vision.

NCERT Extract:
Mendelian Disorders – “… It is a sex-linked recessive disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour. This defect is due to mutation in certain genes present in the X chromosome. It occurs in about 8 per cent of males and only about 0.4 per cent of females.”