Which of the following is a sex-linked character?

The sex-linked character among the given options is color blindness. Sex-linked traits are the traits that are carried on the sex chromosomes (X and Y chromosomes). In humans, the sex chromosomes are XX in females and XY in males. Since males have only one X chromosome, they are more likely to express the traits carried on the X chromosome. Color blindness is a recessive trait that is carried on the X chromosome. Therefore, males have a higher chance of expressing color blindness than females. Sickle-cell anaemia is an autosomal recessive trait, meaning it is not carried on the sex chromosomes. Tongue rolling and skin color are also not sex-linked traits and are not determined by the sex chromosomes.