Ans.
A sex-linked trait is defined as character, determined by the genes present on sex chromosomes. In humans, females have two sex chromosomes (XX) and a heterozygous individual shows presence of different or alternative alleles for a trait.
Therefore, a female showing heterozygous sex-linked trait will show XRXr as one of its X chromosome carries wild type allele (R), while another X chromosome carries mutated (r) allele.
Thus, the correct answer is 'option). XRXr.'
